RI 1 T~E CARBAMATE REACTION OF HUMAN HEMOGLOBINS

G.Gros and R.E.Forster

We have measured the formation of carbamate in hemoglobin solutions using the stopped flow rapid pH technique described previously. For human adult hemoglobin carbamate concentrations were determined in a wide range of pH (pH 6 - pH 8.5) and pC02 (30-140 Torr) in fully oxygenated and fully deoxygenated solutions. Analysis of the results indicated that 3 kinds of groups participate in carbamate formation of deoxyhemoglobin: 2s-NH2 groups (u-chains), 2a-NH 2 groups (S-chains), and -15 c-NH2 groups. Upon oxygenation the contribution of thea-NH 2 groups of the S-chains appeared to vanish. AHbCO2/AHb02, the fraction of oxylabile carbamate, is -0.2 for stripped HbA with pH=7.2 and pCO2=40 Torr. Using a least squares procedure the carbamate equilibrium constants, Kc, and the ionization constants, Kz, were calculated for the three types of groups. In hemoglobin solus prepared from cord blood measurements were performed at pH 6.5-8 and pCO2 = 140 Torr. The data indicated that, in the absence of 2,3-DPG, fetal hemoglobin has the same carbamate affinity as adult hemoglobin. Similarly, the fraction of oxylabile carbamate seemed to be identical for the two stripped hemoglobins. ~arbamate formation i n m e t h e m o g l o b i n was not significantly different from that in oxyhemoglobin, and addition of dithionite led to an increase in carbamate to the values seen in deoxyhemoglobin. Experiments in presence of 2,3-DPG showed that the interaction of CO2 and DPG is equally strong in adult as well as in fetal oxyand deoxyhemoglobin. Institut f~r Physiologie, Universit~t, D-84 Regensburg, Postfach Dept. of Physioloqy; Univ.Penn., Philadelphia, Pa. 19174, USA

2 O N THE INFLUENCE OF GLUTATHIONE ( GSH ) ON THE O^ Hb BINDING CURVE AND THE BOHR FACTOR IN ERYTHROLu UNDER IN VIVO ZCONDITIONS W.K.R. Barnlkol In 1970 HOREJSI has reported (Adv.Exp.Medicine and Biology, 6,9-20 ), that within the physiological range of concentrations and under normal conditions glutathlone causes a shift tothe right of the O^ Hb binding curve of whole blood. On the other hand PANIKER and BEUTLER ( Proc.Exp.ZBioI.Med., 1970, 135,389-391 ) did not find any influence of oxidized glutathione ( GSSG ) on the 0 2 Hb binding curve. They investigated purified Hb solutions ( 5g/100 ml ) by a mixing technique with and'without addition of 2,3- DPG. The intracellular concentration of glutathlone is 3.6 mM/L ( ref. to free water ) and the percentage of the GSH form is 90. The cited findings and high intracellular molar concentration of GSH, which is in the order of the Hb concentration ( 5 mM ), gave rise to reinvestigate the problem under own experimental conditions. Fresh blood was centrifugated and the packed red cells were cryollzed with liquid air. i2.1 mM/L glutathione ( GSH ) were added. The O~ Hb binding curve was measured microphotometrically at PCO^ = 40 Tort and 37~ ( BARNII~OL, WAHLER, 1973, Adv.Exp.Medicine and Biology 37 A, :4325- 331, Plenum Press ). The spontaneous shift of the 0 2 Hb binding curve after venipuncture was corrected by measuring the time dependence and extrapolation. Within the reproducibility of the method ( ~ + 0.2 Torr for P'0 ) no influence was found, neither on the 0 2 Hb binding curve itself n ~ o n the BOHR fa~ctor. From these findings follows, that glutathione ( GSH ) is not an effector of the OgHb binding curve. So the experimental conditions may be varied without regard to the GST-I concentration. Physiologisches Institut, Universlt~t Mainz, 65 Mainz, Saarstr. 21

R2 3 COMPARATIVE STUDIES OF HEMOGLOBIN FROM LOWLAND AND HIGHLAND MAMMALS AND BIRDS D. P e t s c h o w , R~ B a u m a n n , I. W ~ r d i n g e r a n d C. B a u e r The respiratory properties of hemoglobin from two animals normally l i v i n g at h i g h a l t i t u d e s n a m e l y t h e g u a n a c o (Lama ~ u a n i c o e ) as a m a m m a l a n d t h e b a r - h e a d e d g o o s e (Anser i n d i c u s ) as a b i r d , h a v e b e e n c o m p a r e d w i t h t h o s e o f m a n a n d t w o g e n e r a o f g e e s e (Anser a n s e r and B r a n t a c a n a d e n s i s ) w h o u s u a l l y r e s i d e a t s e a l e v e l . W h o l e b--i~od o x y g e n a f f i n i t y a t p H = 7 . 2 , p C O 2 = 4 O m m H q a n d 3 7 o c w a s f o u n d to b e h i g h e r in t h e t w o " h i g h l a n d e r s " ( P 5 0 = 2 3 . 3 a n d 2 9 . 7 m m H g in g u a n a c o a n d A. i n d i c u s r e s p e c t i v e l y ) c o m p a r e d t o b e c o r r e s p o n d i n g " l o w l a n d e r s " ( m a n : 2 6 . 6 m m H g ; B. c a n a d e n s i s : 3 9 . 5 m m H g a n d A. a n s e r : 4 2 m m H g ) . In t h e a b s e n c e o f o r g a n i c p h o s p h a t e s t h e o x y g e n a f f i n i t y o f h e m o g l o b i n f r o m t h e g u a n a c o is l o w e r t h a n o f h u m a n h e m o g l o b i n b u t is v e r y w e a k l y a f f e c t e d b y 2 , 3 - D P G . T h e h i g h e r o x y g e n a f f i n i t y of t h e g u a n a c o b l o o d c a n t h e r e f o r e b e e x p l a i n e d b y a r e d u c e d i n t e r a c t i o n o f g u a n a c o h e m o g l o b i n w i t h 2 , 3 - D P G c o m p a r e d to h u m a n h e m o g l o b i n . T h e h e m o g l o b i n o f A. i n d i c u s , e x h i b i t s a n i n t r i n s i c a l l y h i g h e r o x y g e n a f f i n i t y as c o m p a r e d to A. a n s e r a n d B. c a n a d e n s i s . In all t h r e e b i r d h e m o g l o b i n s t h e o x y g e n a f f i n i t y is d r a s t i c a l l y reduced by inositol hexaphosphate (IHP). A t a g i v e n c o n c e n t r a t i o n o f IHP, t h e h e m o g l o b i n o f A. i n d i c u s h a s a h i g h e r o x y g e n a f f i n i t y t h a n t h a t o f A. a n s e r and B. c a n a d e n s i s . It a p p e a r s f r o m t h i s s t u d y t h a t a h i g h o x y g e n a f f i n i t y is e n c o u n t e r e d n o t o n l y in m a m m a l s b u t a l s o in b i r d s w h o l i v e a n d b r e e d in a l t i t u d e s o f m o r e t h a n 4000 meters. Dr.

D.

Petschow,

Physiologisches

Institut

der MHH,

D 3 Hannover

4 THE PROPORTION OF FACILITATED OXYGEN TRANSPORT AT DIFFERENT OXYGEN TENSIONS ~ T THE HIGH- A ~ LOW-PRESSURE SI~ES OF HEMOGLOBI{-LOADED MILLIPORE MEMBRANES. Ch. Weigelt , W. A. Grunewald , D._W. Ltibbers (supported by VW-Stiftung) In the presence of hemoglobin oxygen is transported by facilitated diffusion in addition to the diffusion of the physically dissolved oxygen. For the facilitated transport by hemoglobin an oxyhemoglobin(PIbo2)-concentration gradient over the diffusion path is required. Such a gradiens could be directly measured in hemoglobin-loaded millipore membranes by kryophotometrically registering HbO2-saturation profiles (Weigelt et al., PflOgers Arch. 339, R 4 (1973)). This gradient was investigated by changing the oxygen tension (Po2) at the low pressure side of the membrane from zero to 15 mm Hg but maintaining the Po~ difference between the low-pressure- (LPS) and high-pressure sides (HPS) aT a constant value. I) E. q., for a Po 2 difference of 15 mm Hg (LPS-HPS) and at zero mm Hg (LPS) the portion of oxygen transport effected by facilitated diffusion of the hemoglobin is about 5 times higher than the oxygen transport by diffusion in a solution without hemoglobin. When the LPS oxygen is raised in steps of 5 mm Hg up to 15 mm Hg the facilitated flux decreases, but even at 15 mm Hg the facilitated flux is twice as high as without hemoglobin. 2) F o r a Po~ difference of 72 mm Hg the total flux increases because of the higher gradient. However, due to the HbO 2 gradient, the faciiitated flux is only about 1.5 times higher than the flux without hemoglobin. The maximal facilitation by the hemoglobin was attained with zero mm Hg Po 2 at the LPS and a Po 2 at the HPS which was in the steepest part of the Hbo2-dissociation curve. Our experimental findings are in good qualitative agreement with the theoretical calculations of Kreuzer and Hoofd (Resp. Physiol. (1970) 8, 280). i) Max-Planck-Institut f~irSystemphysiologie, D-46 Dortmund, Rheinlanddamm 201 2) Physiol. Institut der Universit~t Regensburg, D-84 Regensburg, Universit6tsstr. 31

R3 5 THE RELEASE R E A C T I O N AND SHEAR INDUCED P L A T E L E T A G G R E G A T I O N H. Rieger +) and H. S c h m i d - S c h ~ n b e i n The release r e a c t i o n (RR) is commonly c o n s i d e r e d as the functional substrate of p l a t e l e t a g g r e g a t i o n (PA). This a s s u m p t i o n is based on e x p e r i m e n t a l m e t h o d s in w h i c h PA is induced by the addition of ADP e p i n e p h r i n e or collagen and is r e l a t e d to the accompaning release reaction. On the other hand, a g r e a t number of ant i a g g r e g a t i n g agents are capable to inhibit both PA and RR simultaneously. In the a t t e m p t to elucidate the nature of spontaneous, shear induced PA in v i s c o m e t r i c flow (RIEGER et al. Pfl~gers Arch. 343, R33, 1973) the release of C 1 4 - s e r o t o n i n in resting, non aggregating PRP as well as after p r o n o u n c e d shear induced PA was studied. D e s p i t e of a strong a g g r e g a t i o n (35.8% ~ 13) we found only 1.4% + 1.6 release. Even c h e m i c a l l y p o t e n t i a t e d a g g r e g a t i o n by ADP and e p i n e p h r i n e (I ~M, 22~ p r o d u c e d p r o n o u n c e d PA (63% + 5 and 59% + 3.7, resp.) but failed to release C 1 4 - s e r o t o n i n (1.2% + ~.O, 2.9% + 2.0, resp.). These latter results c o n f i r m e a r l i e ~ ones by V A L D O R F - H A N S E N and ZUCKER, 1971. These results shed further doubts on the concept that in vivo PA m i g h t only be p r o v o k e d by a locally liberated chemical messenger. P h y s i c o c h e m i c a l changes on the p l a t e l e t - p l a s m a b o u n d a r y altered e l e c t r o s t a t i c i n t e r a c t i o n b e t w e e n d e f o r m e d p l a t e l e t s and injured endothelium, and m o s t of all the m e c h a n i c s of c o l l i s i o n are m u c h m o r e likely factors o p e r a t i o n a l in p l a t e l e t function. Dept.Physiol., Techn.Univ. D-51 Aachen, M e l a t e n e r Str. 211. S u p p o r t e d by the D e u t s c h e F o r s c h u n g s g e m e i n s c h a f t (Ri 251/2).

THE ROLE OF THE E.R. Zimmermann,

CARBOHYDRATE W. Menzel,

MOIETY IN FIBRINOGEN H. Berg, and K.-P. V61kl

Fibrinogen contains small amounts of mannose, galactose, glucosamine and sialic acid. Since the carbohydrate content of fibrin is about 12 % less than ~hat of fibrinogen it is to assume that the carbohydrate moiety is an essential part of the fibrinogen molecule. LAKI and CHANDRASEKHAR concluded on their observation with sialic acid-free fibrinogen that the LAKI-LORAND-factor depends on the intaclness of the fibrinogen substrate (Biochim~ e! Biophys. Acta 93, 292, 1964). Fibrinogen used in the following experiments was prepared according to BLOMBACK' s procedure. Clotting was brought about with pure bovine thrombin (E.C.3~176 and the rate of clotting was followed in a HARTERT-thrombelastograph. In order to study the effect of carbohydrate liberating enzymes as neuraminidase or glucosidase as well as galactosidase, fibrinogen was subjected to the aclion of this enzymes in suitable reaction mixtures. Our results demonstrate clearly that the fibrinogen clots faster while the stability of the clot is drastically reduced. Department of Physiology Robert Koch-Strafe 28

If, University

of Miinster,

D

44 M finster,

R4 7

THE STABILITY LATORY SYSTEMS

OF

HUMAN FIBRINOGEN W~ Menzel, H. Berg,

IN EXTRACORPORAL CIRCUEoR~ Zimmermann and Mo Schwale

Studies performed mainly by BLOMB~CK and his cow orkers o n fragmentation of the fibrinogen molecule by chemical means have provided a solid basis for the concept of its three-dimensional structure. Fragmentation of fibrinogen by various enzymes is known to produce a great variety of products. The first group of derivatives is produced by thrombin-like enzymes, which have limited proteolytic activity. In comparison, the plasminlike enzymes have a far more extensive proteolytic activity and the fragments produced are of greatest pathophysiological importance (V,J. MARDER et al. JoBiol. Chem. 244,2111 (1969))o Comparative studies of the behavior of plasmin ac!ivators and their effect upon the fibrinogen structure disclosed the fact that in spite of an extensive plasminogen activation during extracorporal circulation periods only a limited plasmin-mediated fibrinogen degradation occured. The process of digestion under extracorporal circulation conditions was monitored by several electrophoretical technics, including disc gel, agar gel and immunelectrophoresis~ The molecular weight distribution of the individua ! products was measured by sedimentation analysis. In conclusion, the available data indicated that the prolongation of the clotting time after extracorporal circulation experiments is due to these early fibrinogen intermediates of a limited plasminmediated fragmentation~ Department of Physiology Robert Koch-Stra6e 28

II, University

of M[inster,

D 44 M[inster,

8 ON A C T I V A T I O N A N D F U N C T I O N O F H A G E M A N - F A C T O R IN B L O O D CLOTTING AND FIBRINOLYSIS W. A u e r s w a l d , B. B i n d e r , EE. H a t t e y , M. K o c h , G. K r u g , M. P a w e l k a , a n d T h . V u k o v i c h P r e v i o u s s t u d i e s p r o v e d the e s s e n t i a l r o l e of H a g e m a n - F a c t o r ( F X l l ) a n d p h o s p h o l i p i d s ( P L ) in s t a r t i n g b l o o d cl~)tting, f i b r i n o l y s i s , and kinin forma= t i o n . T o e l u c i d a t e t h e f a t e of F X l l d u r i n g a n d a f t e r a c t i v a t i o n a n d i t s i n t e r = action with PL we used a model, i.e. highly purified FXII and FXI prepara = tions, a part}ally purified perivascular plasminogen activator (angiokinase, A K ) , k a o l i n , a n d P L . , W i t h k a o l i n a l o n e F X I I is a c t i v a t e d . . a n d a d s o r b e d ; F X I l a in t h i s f o r m d o e s n o t a c t i v a t e p u r i f i e d F X I . W i t h P L a l o n e F X I I a l s o u n d e r g o e s a c t i v a t i o n a n d t h i s F X l l a is c a p a b l e of f o r m i n g F X l a , a l t h o u g h c o n v e r s i o n to F X I l a i s c o m p l e t e d o n l y a f t e r h o u r s . W i t h a m i x t u r e o f k a o l i n a n d P L t h e r e is r a p i d f o r m a t i o n of F X I l a w h i c h to i t s g r e a t e r p a r t is b o u n d to P L a n d t h e r e f o r e a b l e to a c t i v a t e F X I . In gel f i l t r a t i o n i t w a s s h o w n t h a t the P L i n v o l v e d a r e p r e s e n t a s m i c e l l a r c o m p l e x e s ; t h e s e m i c e l l a r P L w e r e demonstrated ultramicrographically. W i t h r e g a r d to t h e f i b r i n o l y t i c s y s t e m t h e r e is e v i d e n c e t h a t p l a s m i n o g e n a c t i v a t o r u n d e r g o e s a l s o a d s o r p t i o n to PL retaining thereby its full activity while plasmin remains unadsorbed. T h e f u n c t i o n a l i m p o r t a n c e of P L - a p l a t e l e t c o n s t i t u e n t in v i v o - a p p e a r s to be in v i e w of t h e s e f i n d i n g s to f o c u s the i n d u c t i o n of b l o o d c l o t t i n g a n d the a c t i v a t i o n o f c l o t d i s s o l u t i o n . ( S u p p . b y a G r a n t f r o m the A u s t r . F u n d f. P r o m o t . o f S c l e n t . R e s . ~ P r o j . NP. 1 8 0 0 ) D e p t s . of P h y s i o l . a n d U l t r a s t r u c t . R e s . U n i v . of V i e n n a , A - 1 0 9 0 Schwarzspanierstr. 17.

R5 9

ISOELs

FOCUSING OF PURIFIED HUMAN ANTIHEMOPHILIC FACTOR PREPARATIONS

H. Assmann end W. Doleschel Antlhemophllic factor in human blood occurs as a macmomolecule with a molweight of 1.1xi06 o r higher. AHF molecules consist of subunlts dlsputedly claimed to be linked either by disulfide bridges (P.A.McKee et el., Ann.N.Y. Acad.Scl. 240. 8, 1975) or by non-covalent bonds (L.W.Hoyer, Ann.N.Y.Acad. Sci. ~

84, 1975). In the present investigation partlally purified factor

VIII preparations, when filtered on Sepharose 4B, appeared only in the void volume; when subjected t o isoelec%Tic focusing (Ampholine pH 3-10), at least 4 active subfractions could be distinguished. The pmscoagulant activity of

these fractlons following reconcentration varied with respect to their stability at 4~

Refiltmation of the 3 main subfz~ctions on Sepha~se 48

gave active products of different molecular weights, e.g.>Ix106 Daltons, 2-3.10 s Daltons end values between these extremes for p~oducts of minor activity. The results suggest that human ?actor VIII exists in more than one molecular form and/or an active procoagulant mulecule is bound to carrier proteins of different isoelectric value. Physiol. Inst. Univ, Wisn, A 1090, SchwarzspanierstraBe 17 10

PLATELET A G G R E G A T I O N COMPLEMENT

IN VITRO:

SOME INVESTIGATIONS WITH THE

D E R I V E D PEPTIDE C'5a. K.U. Banner,

H.G. Classen,

and P. Marquardt.

Anaphylatoxin

(AT), a peptide

the complement

K.A.

Schumacher,

splitted from the 5. component of

system was prepared

from rat plasma either by incu-

bation with low m o l e c u l a r weight d e x t r a n

(MW 2,000)

at 370C or by

treatment with cobra venom factor. With the n e p h e l o m e t r i c

method

of Born the effect of AT was studied on platelet rich plasma from man, dog, rabbit, cat, guinea pig, and rat. From all species tested only the platelets from cat and guinea pig reacted upon the addition of AT. Experiments with E D T A i n d i c a t e d

that aggregation

induced hy AT depends upon the presence of divalent cations in the plasma.

Several known inhibitors of aggregation

tion, e.g. phentolamine, p-chloromercuribenzoate gregation.

Adenosine,

leate, however,

and platelet

tosylarginine m e t h y l e s t e r

func-

(TA~4e), and

(PCMB) were found to reduce AT induced ag-

methysergide

bimaleinate,

remained ineffective.

and m e p y r a m i n e ma-

The TAMe- and P C M B - e x p e r i -

ments suggested that AT reacts with the platelets via a release reaction. In~i%u%f~r n o r m a l e u n d pathologische Physiologie de r Univers~tj D-5000 K61n, Robert-Koch-Strafe39

R6 11 ON A N E V O L U T I O N A R Y R E G U L A R I T Y IN THE R E L A T I O N S H I P OF SOME H/~EMATOLOGICAL AND B I O C H E M I C A L BLOOD P A R A M E T E R S IN VERTEBRATES. V. P a v 1 o v i 6 -

The analysis of the data o b t a i n e d through our own researches, or of the data from l i t e r a t u r e , i n c o n n e c t i o n w i t h h a e m a t o l o g i c a l and b i o c h e m i c a l b l o o d p a r a m e t e r s in vertebrates, points out to an e x p r e s s e d e v o l u t i o n a r y regularity. Namely, among all the classes of vertebrates, a m p h i b i a n s have a special p o s t i o n in this respect. The r e p r e s e n t a t i v e s of this class of v e r t e b r a t e s have the s m a l l e s t n u m b e r of e r y t h r o c y t e s in one c m m o f blood, but their d i a m e t e r is the largest; Hb c o n c e n t r a t i o n in some e r y t h r o cytes is higher than in any other class. The q u a n t i t y of a l b u m e n in the smallest, the one of g l o b u l i n p r o p o r t i o n a l l y the greatest; albumen ratio in only about 0.2 w h i c h represents the lowest value among vertebrates. The e r y t h r o c y t e s s e d i m e n t a t i o n after 1 and 2 hours shows i n c o m p a r a b l y higher values than in any other class of vertebrates. According to the values of these blood p a r a m e t e r s and the speed of e r y t h r o c y t e s sedimentation, r e p t i 1 e s come afs amphibians, and then f i s h e s, b i r d s and finally m a m m a 1 s. W i t h i n some classes there are deviations, of course, (particularly in mamals), but they f o l l o w the p a t t e r n of general r e g u l a r i t i e s r e g a r d i n g the number of e r y t h r o c y t e s I Hb c o n c e n t r a t ion and the speed of e r y t h r o c y t e s sedimentation. P h y s i o l o g y d i v i s i o n of the B i o l o g i c a l Institute, D e p a r t m e n t of Animal P h y s i o l o g y of the F a c u l t y of Natural Sciences and M a t h e m a tics - The U n i v e r s i t y of Sarajevo, V o j v o d e P u t n i k a 43. Y u g o s l a v i a 12 E F F E C T OF RENAL H Y P E R T E N S I O N ON THE I N T R A C E L L U L A R B U F F E R I N G OF C A R D I A C AND S K E L E T A L M U S C L E C. Albers, M. M a l y u s z and W. H e r t e n

_

P r e v i o u s e x p e r i m e n t s (SABOROWSKI, et al., Resp. Physiol., 18, 171, 1973) d e m o n s t r a t e d a m a r k e d increase in i n t r a c e l l u l a r b u f f e r i n g of the c a r d i a c m u s c l e in the early stage of h y p e r t r o p h y caused by subd i a p h r a g m a t i c c o n s t r i c t i o n of the aorta (AC). D u r i n g chronic h y p e r trophy after AC, the b u f f e r values r e t u r n to control values (HERTEN u n d ALBERS, V e r h . D t s c h . G e s . K r e i s l a u f f o r s c h . , 1975). The p r e s e n t e x p e r i m e n t s aim at the b u f f e r i n g of cardiac and skeletal m u s c l e d u r i n g chronic renal h y p e r t e n s i o n (RH) due to u n i l a t e r a l c l a m p i n g of the renal artery in W i s t a r rats. The m e a n arterial blood p r e s s u r e 4-6 w e e k s after the o p e r a t i o n was 151 torr (control rats 110 torr), the ratio of heart w e i g h t to body w e i g h t 3.5 x 10 -3 (2.8 x 10-3), the i n t r a c e l l u l a r pH (at paCO 2 = 40 torr) 6.89 (6.91). In c o n t r a s t to cardiac h y p e r t r o p h y due to AC, RH causes a sharp d e c r e a s e in the i n t r a c e l l u l a r b u f f e r i n g from 78 to 25 slyke. W h e r e a s i n t r a c e l l u l a r b u f f e r i n g of skeletal muscle is not a f f e c t e d by AC, RH reduces the b u f f e r value from 23 to 7 slykes. These effects are p o s s i b l y m e d i a t e d by angiotensin. I n s t i t u t fHr P h y s i o l o g i e der U n i v e r s i t ~ t D-84 Regensburg, P o s t f a c h Institut f~r P h y s i o l o g i e der U n i v e r s i t ~ t D-23 Kiel, P o s t f a c h

R7 13 H E M O D Y N A M I C P A R A M E T E R S OF A W O R K I N G I S O L A T E D G U I N E A PIG H E A R T AS I N F L U E N C E D BY D I F F E R E N T C A R B O H Y D R A T E S . R . B H n g e r and E . G e r l a c h Studies on the isolated guinea pig h e a r t (PflHgers Arch, 353,317, 1975) h a v e b e e n extended to a p r e p a r a t i o n p e r f o ~ n i n g p r e s s u r e volume work. A m o d i f i e d o x y g e n a t e d K r e b s - R i n g e r - b i c a r b o n a t e solution (38oc, pH 7.4) s u p p l e m e n t e d with fructose, glucose or pyrurate was used as c i r c u l a t i n g medium. It was applied into the left a t r i u m and ejected by the left v e n t r i c l e via an aortic cannula into an o v e r f l o w vessel (hydrostatic p r e s s u r e 75 cm H20). SPOntaneous h e a r t rate, left atrial pressure(LAP), aortic p r e s s u r e
R8

15 DYNAMICS OF THE INTERSTITIAL SPACE OF THE MYOCARDIUM EVALUATED BY WASH-IN AND WASH-OUT BEHAVIOUR OF MARKER SUBSTANCES OF THE EXTRACELLULAR SPACE H. Kammermeier, B. Kammermeier Marker substances of the extracellular space are washed-out from the heart according to multiexponential kinetics. Detailed evaluation indicated that the interstitial space is kinetically devided into two compartments with different rate constants of wash-out, both behaving as r e a l well-stirred compartments. It seemed of particular interest whether uptake of the markers takes place according to the same rate constants as the washout. Evaluation of special experiments (integration of wash-out kinetics of hearts exposed t o d i f f e r e n t wash-in periods) showed the latter to hold true. This finding supports the idea that the myocardial interstitial space is formed by two kinetically different compartments, which behave as parallely structured. The numerical data support further I) earlier findings according to which the transcapillary exchange of hydrophilic small molecules takes place slowly as compared to data published so far and 2) earlier conclusions indicating that capillary exchange can be a rate limiting process in the myocardial metabolism. Dept. Physiol., Techn.Univ., Melatener Str. 211

Med.Fac.,

D-51 Aachen,

16 RELEASE OF ADENOSINE DURING ISOPEOTERENOL- AND ACETYLCHOLINEINDUCED CORONARY VASODILATION. J .Schrader, G.Hiendlmayer, E .Gerlach Isoproterenol(ISO) increases coronary flow and 02-requirement of the heart, whereas acetylcholine(ACh) induces coronary dilatioD without increasing myocardial O2-consumption. In order to elucidate whether adenosine(AR) might be involved in the vasodilatory effects of ISO and ACt, experiments were performed on isolated ~uinea pig hearts perfused with a modified Krebs-Henseleit-solution (Pfl~gers Arch. 353:317,1975). Under control conditions , concentrations of AR, inosine(HR) and hypoxanthine(H) in the cardiac perfusate were 5.2, 81.8 and 13.7 nM, respectively. ISO (4 x iO-8~ increased coronary flow (+7~%) and perfusate concentrations of AR, H R and H to 137, 833 and 80 raM, respectively. Propranolol (3.9 x IO-7M) completely inhibited the ISO-induced vasodilati~n and the enhanced release of the purine compounds. ACt (2 x IO-~M) caused coronary flow to increase (+ii~%) concomitant with a rise in the perfusate concentrations of AR, H R and H to 102, 259 and 22.5 nM, respectively~ Atropin (1.4 x IO-6M) blocked the metabolic and hemodynamic changes induced by ACt.- Since the threshold concentration of AR for eliciting coronary dilation is in the order of 80 nM, AR formed and released under the influence of ISO and ACh appears to be quantitatively sufficient to mediate the coronary dilation induced by these compounds. From the experiments with ACh it becomes furthermore evident that an increased formation of AR can also occur under conditions in which O2-supply to the myocardium is not critical. Department of Physiology,

University of Munich, D-8 Mttnchen 2

R9

17 INFLUENCE OF CALCIUM, ISOPROTERENOL AND COMPOUND D 600 ON CONTRACTILITY, 3' :5'-CYCLIC AMP AND GLUCOSE-PHOSPHATES OF THE MYOCARDIUM. H.-G. Zimmer, R. Bringer, E. Gerlach In order to elucidate possible relations between myocardial contractility and changes in the levels of cardiac 3':5'-cyclic AMP (cAMP), glucose-l-phosphate(G-1-P) and glucose-6-phosphate(G-6-P), studies were performed on isolated rat hearts perfused at constant pressure with a modified Krebs-Ringer-bicarbonate solution (PflQgers Arch. 353,317,1975). Left ventricular pressure(LVP) and dP/dtma x were recorded. Myocardial concentrations of cAMP, G-I-P and G-6-P were determined iO or 20 min after steady performance of the hearts was obtained upon perfusion with different calcium concentrations, isoproterenol (1.3 x IO-SM) and D 600 (2 x IO-7M), respectively. Elevation of the calcium concentration from 2.5 to 7.5 meq/l caused an almost fourfold rise of peak LVP and dP/dtmax, whereas the levels of cAMP, G-I-P and G-6-P did not change signi-" ficantly. Isoproterenol increased contractility by about 300% and the levels of cAMP, G-I-P and G-6-P by about 2009. Isoproterenol in the presence of D 600 did not affect contractility, but the concentrations of cAMP, G-I-P and G-6-P were still considerably elevated. It thus appears that cardiac contractility can be altered independently of changes of cAMP levels and cAMP-mediated metabolic reactions. The results are in agreement with previous findings on rat hearts in vivo (Verh.Dtsch.Ges.Kreislaufforsch. 40,348,1974), according to which the effects of isoproterenol on heart performance were dissociated by D 600 from those on cAMP concentration and on the biosynthesis of adenine nucleotides. Physiologisches Institut der Universit~t M~nchen 18 THE LANGENDORFF HEART AS A MODEL FOR ANALYSIS OF MYOCARDIAL ENZYME RELEASE: I. RELATIONS BETWEEN 02 SUPPLY AND ENZYME RELEASE. M.M. Gebhard, H. Denkhaus, K. Sakai and P.G. Spieckermann The conditions which lead to the loss of macromolecular enzymes from the cell into the extracellular space have not, as yet, been fully clarified. Because of the fairly large concentration gradients over the cell membrane a contribution, at least, of active retention processes is quite probable. Experiments were carried out on the isolated perfused Guinea pig heart to clarify the relationships between myocardial enzyme loss (MDH, LDH, CPK) and energy metabolism. In a first group of experiments the O2 supply to the heart was varied. (Total ischemia, hypoxia, anoxia.) The following results were obtained: I. The amount of enzymes washed out during a defined post-ischemic reperfusion period is dependent on the duration of the preceding ischemia. 2. Reduction of the 02 content of the perfusion solution (ioo, 25, Io, 5, O % 02) revealed an inverse dependence of enzyme release on 02 supply which can be described by a simple power function (r = O, 99). Institute of Physiology Humboldtallee 7

I, University

of G6ttingen,

D-34 G6ttingen,

R 10

19 THE LANGENDORFF HEART AS A MODEL FOR ANALYSIS OF MYOCARDIAL ENZYME RELEASE: I I . RELATIONS BETWEEN ENERGY DEMAND AND ENZYME RELEASEL P . G . S p i e c k e r m a n n , H. D e n k h a u s , M.M. G e b h a r d and K. S a k a i

The prevention of enzyme leakiness seems to be - directly or indirectly - an energy consuming process. If this hypothesis be true~ reduction of myocardial energy demand without changing the energy supply must decrease the enzyme release of the cell. For this reason myocardial energy requirements were varied by dru~s and by lowering the perfusion temperature. I. Pretreatment of the experimental animals with reserpine or propranolol results in a significantly lower enzyme release during 5 hours anoxic perfusion as compared with nontreated control experiments. 2. During anoxic perfusionoat 15 and 25~ considerably less enzyme was released than at 35 C. The release of CPK, LDH, MDH phenomenologically follows the Arrhenius equation. The temperature coefficients (QIO) are in the region of those determined for myocardial oxygen consumption and for the break down of high energy phosphates during anaerobiosis. Enzyme release and myocardial ATP content are inversely correlated. Institute of Physiology I, University of G6ttingen, Germany 20 DIFFERENCES IN CONTRACTURE DEVELOPMENT OF THE HYPOXIC HEART IN VARIOUS SPECIES

H. Moser and W. Schnizer

Former investigations on open-chest rabbits demonstrated a measurable decrease of diastolic compliance induced by only 15 sec. oxygen-deficient respiration.

Comparable measurements of the dia-

stolic pressure volume-relationship

on urethane anaesthetised

Wistar rats showed an essentially higher tolerance against hypoxia in this species evaluated on the basis of the diastolic stiffness. Further investigations on dogs revealed an even longer interval before the onset of contracture after the start of hypoxia. However, in no species could a loss of tone caused by hypoxia be demonstrated. The decrease of left ventricular internal volume at a given enddiastolic pressure induced by hypoxia is not dependent on changes of intracoronary blood volume. This was demonstrated by pharmacological

reduction of coronary resistance.

The results will be discussed with regard to morphological and biochemical data from other authors. Institute of Physiology, University of Tuebingen, Gmelinstra~e 5

D 74 Tuebingen,

R 11

21 ANALYSIS OF THE EJECTION PERIOD OF THE HYPERTROPHIED LEFT VENTRICLE OF RATS In r a t s

G. Kissling~ F. Hartmann and R. Jacob a h y p e r t r o p h y of the l e f t

ventricle

o f a b o u t 40 I was p r o -

duced by n a r r o w i n g o f one r e n a l a r t e r y ( G o l d b l a t t I I ) . The a o r t i c flow dV/dt (electromagnetic flowmeter) and the intraventricular pressure were measured simultaneously. Instantaneous heart volume was calculated from the difference of the enddiastolic volume and the ejected volume. Following results were obtained: For a given enddiastolic volume the stroke volume is the same in Goldblatt and control rats. Peak aortic flow (dV/dtma x) is slightly diminished and is attained at a later time. The acceleration of the aortic s d2V/dt 2 is signis decreased while the ejection time is prolonged. As a result of the thickening of the wall the systolic ventricular wall stress was not enhanced, although ventricular pressure was increased markedly. The correlation of the calculated shortening velocity for a given ventricular volume with, the instantaneous wall stress does not prove a significant impairment os s shortening due to wall hypertrophy. Institute of Physiology II,University of D 74 Tuebingen,Gmelinstr.5 22 PASSIVE ELASTIC PROPERTIES OF THE HYPERTROPHIED RAT VENTRICULAR MYOCARDIUM

A. Kamme~eit and R. J a c o b

Comparing two forms of hypertrophy of rats' myocardium (a mild one' produced by chronical swimming training; and a m a r k e d Goldblatt hypertrophy) - there was, apart from some divergences (Vma x and maximum instantaneous power), a clear tendency towards an increase in stiffness of the hypertrophied myocardium. This alteration, however, is not due to an augmentation of the connective tissue in this stage, as examination of the hydroxyproline concentration proved. In any case, the altered passive properties of the myocardium have consequences for the determination of Vma x on the basis of isotonic QR-experiments. An increase of the initial contraction velocity caused by an enhanced passive component, has to be expected' If the augmentation of myofibrillar protein concentration is considered as a possible cause of the altered elastic properties, contradictions to some generally accepted muscle models would necessarily Occur. Institute of Physiology II,University of D 74 Tuebingen,Gmellnstr.5

R12 23 MYOFIBRILLAR PROTEIN-CONCENTRATION,

CALCIUM-ATPase ACTIVITY AND

CONTRACTILE CAPABILITY OF THE HYPERTROPHIED RAT MYOCARDIUM I. Medugorac, A. K~mmereit and R. Jacob In young male Wistar rats a coarctation of one renal artery during a period of four weeks (Goldblatt hypertension) led to an increase in the left ventricular weight of 40 % as compared to the unoperated controls of the same age. Young male Sprague-Dawley rats conditioned by a long-term swimming training showed an average increase in heart weight of 12 % in comparison with control rats. The concentration of hydroxyproline was unchanged. Whereas in both groups of hypertrophied hearts a significant increase in the concentration of myofibrillar proteins

(mg protein per g fresh tissue)

was found, an increase in the specific Ca++-ATPase activity of myocardial actomyosin (50-60 %) only occurred in swimming rats, associated with alterations in the ultrastructure of myosin. These biochemical results are consistent with our former investigations with respect to the maximum shortening velocity of the unloaded myocardium and the isometrically developed stress. Institute of Physiology, University of Tuebingen, D 74 Tuebingen) GmelinstraSe 5 24 NEW ASPECTS TO THE DYNAMIC STIFFNESS OF CARDIAC MUSCLE. R.W.G~Ich The dynamic stiffness of cat right-ventricular papillary muscle was measured in undamped quick-release experiments.

In contrast

to the commonly accepted linear relationship between stiffness dP/dL and total force P, it was found that the relation dP/dL = C I Pe + C2, where ~ >I, fits the instantaneous elastic behaviour of papillary muscle much better. This is true for the active as well as the quiescent cardiac muscle. The exponent is obtained from a plot of log (dP/dL - C2) versus log P. The discrepancy may be ascribed to the fact that any influence of some internal viscous element on quick-releases is usually disregarded. Consequences of the altered relationship for the

interpretation of muscle dynamics on the basis of muscle models are demonstrated. Institute of Physiology II)University of D 74 Tuebingen,Gmelinstr.5

R 13 25

CARDIAC W E S I C U L A R ATPase UNDER "Ca-UPTAKE" CONDITIONS

M.Schwegler

The calcium accumulating ability of the sarcoplasmic reticulum (SR), which is related to a special Ca-transport-ATPase, plays an important role in the regulation of the contractile behaviour of the myocardium.

Generally, cardiac microsomes are found to be less

active and rather unstable compared to skeletal preparations. The time course of the "extra"-ATP-splitting by vesicles prepared from cat ventricular myocardium was examined. The reaction was followed continuously by a combined optical test system (with ATP regeneration) and tested as well at intervals by analysis of the Pi-content. In the presence of 10 mM Ps or 5 mM oxalate

(as precipita-

ting agents for Ca inside the vesicles) and with 5 - 50 ~M CaCI 2 the cardiac "extra" SR-ATPase exhibits first order saturation kinetics and therefore is tightly coupled to Ca-accumulation. With higher, but not yet inhibitory concentrations of Ca ++ the "extra" ATPase changes to zero order kinetics, indicating an "uncoupling" of the transport system. The cardiac SR transport-ATPase is equally activated by Sr ++ but with a smaller velocity constant. Institute of Physiology II,University of D 74 Tuebingen~Gmelinstr.5 26 FURTHER IMPROVEMENTS IN ARTIFICIAL CARDIAC ARREST WITH SUBSEQUENT ANAEROBIOSIS BY THE COMBINATION OF VARIOUS PARAMETERS. H.J. Bretschneider, D.J. Preu~e, H.Kahles, H. Nordbeck and P.G. Spieckermann

In 1964 the first reports appeared on a low-sodium,calcium-free, novocain-containing cardioplegic solution which considerably increased the ischemia tolerance of the heart in both hypo- and normothermia. Recently a further significant improvement has been achieved by the combination of the previously published principles with the following: a) pH-optimisation; b) substitution of a physiologic buffer Ristidin for the inert Mannitol (previously included to attain proper osmolality) and thereby achieving a slowing down in the drop in pH, while maintaining glycolysis at about the same or higher level; c) improvement in the effectiveness of glycolysis hydrogen acceptor and donator properties of the Histidin; d) favourable membrane stabilizing effects by the polar part of the amino acid molecule. With a cardioplegic solution on this basis the t~T P (the time taken for the ATP concentration to fall to 4 ~mol/g)could be increased up to 500 min at 15~C, in contrast to the previous tAT P of 280 min. This improvement is equivalent to a cooling of the heart o f ~ l O ~ Physiologisches Institut, Lehrstuhl I, Universit~t GSttingen, 34 GStt~ngen, Humboldtallee 7

R 14

27 EXAMINATIONS ON THE VALIDITY OF 30 LEFT VENTRICULAR OXYGEN CONSUMPTION PARAMETERS H e l l i g e , G . , D. B a l l e r , W. J o n a s , H. D u c h a n o v a , H. P r e n n s c h ~ t z - S c h O t z e n a u , H. V e n n e b u s c h a n d H . J . Bretschneider Fhe validity of the hitherto reported left ventricular oxygen consumption determinants and complex parameters was examined in Io closed-chest dog experiments. We analyzed 162 steady states including maximal variation of hemodynamics. For each steady state the estimation of 27 hemodynamic variables was required.The c a l t u l a t e d results from each method were compared with directly measured oxygen comsumption. Correlation coefficients range beween r = o.o19 and r = 0.989. There is no significant correlation beween oxygen Consumption and parameters consisting of cardiac volumes and pressures without regard to time dependence. With the inclusion of heart rate the correlation rises up to r = o.872.Better results are obtained with parameters including the first derivative of ventricular pressure. The complex additive parameter of BRETSCHNEIDER leading to the best result is to be prefered for indirect estimation of oxygen requirement of the heart. Calculations of the influence of technical errors and statistical relationships between the diverse determinants on our results were carried out. In view of the clinical appl.ication of oxygen consumption parameters the relation of technical and clinical expense to reliability of the results is discussed. 28 OPTIMISATION 0F HEMODYNAMIC PARAMETERS FOR THE ESTIMATION OF VENTRICULAR OXYGEN CONSUMPTION AND EVALUATION OF THE FUNDAMENTAL LIMIT 0P ACCURACY. Jonas, W., D. Baller and G. Hellige The hemodynamic data on 162 steady states in 10 closed chest dog experiments were analyzed statistically as follows: i. The quantitative Or-consumption parameter reDorted by BRETSCHNEIDER was optimis~d by variation of the constants k to k of the 5 additive subformulas, o 4 2. Further practicable parameters with quite good correlations to directly measured oxygen consumption were optimised by mathematical transformations. 3. The limit of accuracy of tested parameters was calculated by analysis of the measuring technical errors of the respectively applied primary hemodynamic determinants. Assuming an absolute accuracy of the parameters we estimated the maximal obtainable correlation. Our results show that the use of suitable determinants of oxygen consumptions can lead, in practice, to results whose limits of accuracy are determined, in most part, by purely technical and instrumental errors. Physiologisches D-34 G~ttingen,

Institut, Lehrstuhl Humboldtallee 7,

I, Universit~t

G6ttingen,

R 15

29

CHANGES OF ELECTROLYTES AND TRACE METALS IN MYOCARDIAL TISSUE DURING EXPERIMENTAL iSCHEMIA AND ANOXIA. H. K a h t e s , H. N o r d b e c k , C.J~. Preu~e, P.G. Speckermann and H.J. Bretschneider Myocardial infarction has beenproduced in 14 mongrel dogs by ligation of the ramus descendens anterior coronariae sin~strae. After ligation (36o min) and reperfusion (9omin) sodium, potassium, calcium, magnesium, zinc, copper and manganese in the myocardium were determined. In the ischemic areas compared with non-ischemic tissue changes were found which suggest that during ischemia intra-extracellular concentration gradients were reduced. This effect was greater in central infarction areas, and lower in periinfarction areas. A detectable loss by way of-coronary blood and lymph could be shown only for potassium, magnesium and zinc. In the second group of experiments isolated Guinea pig hearts were subjected to an anoxic perfusion under standardized conditions. The changes of electrolytes and trace metals were compared with those of myocardial metabolic indicators. Physiologisches Institut, Lehrstuhl I, Universit~t G~ttingen, 34 G6ttingen, Humboldtallee 7 3O STUDIES OF MYOCARDIAL LYMPH FLOW BY CONTINUOUS FLOW MEASUREMENT, H. Nordbeck, H. Kahles, C.J. PreuBe, P.G. Spieckermann and H.J. Bretschneider Inserting a special catheter in a cardiac lymph vessel and c o l l e c t i n g t h e c a r d i a c lymph we f o u n d , by w e i g h i n g , a mean c a r d i a c lymph f l o w o f 300 n l / m i n " g (n = 4 4 ] . I n 10 e x p e r i m e n t s cardiac lymph flow was continuously determined by electronic weighing and differentiation of the lymph effluent. Thus even fairly rapid changes in cardiac lymph flow can be measured. Additionally, in all experiments, myocardial blood flow (electromagnetic flowmeter], left ventricle pressure (catheter-tipmanometer), dp/dt and, if necessary, total serum protein were determined. The following results were found: I. Cardiac lymph flow is nearly indepe~Ident of coronary blood flow (Dipyridamol) so long as myocardial energy demand remains nearly constant. Z. Under cardiac stimulation with Isoprenaline and Noradrenaline and variation of myocardial energy demand by a factor of 4 cardiac lymph flow increases up to the same factor. 3. A decrease of total serum protein to about a quarter of normal was followed by an increase of cardiac lymph flow up to a factor of I0. Physiologisches Institut, Lehrstuhl I, Universit~t Gettingen, 34 G~ttingen, Humboldtallee 7.

R 16 31 RELATIONS OF MYOCARDIAL pH TO DIFFERENT METABOLIC STATES IN INDUCED CARDIAC ARREST IN DOG, CALF AND MAN. J. Radke, H. Prennsch~tz-Sch~tzenau, H. Nordbeck, J. Schaper, D. Knoll, P.G. Spieckermann and H.J. Bretschneider Previous studies in the dog have shown a correlation of the intramyocardial pH and myocardial ATP-content in different kinds of induced cardiac arrest (B.Lohr et al, PflOgers Arch.319, R 18, 1970). The purpose of this investigation is to support this concept in two further species. Although in calf's heart, in contrast to the dog, a different pattern of Pkr, ATP and Lactic acid changes in myocardium is found, there was a good correlation between ATP-content and myocardial pH during ATP-degradation (r=O,89). The reasons for these findings will be clarified. During the course of ATP-degradation in isolated human myocardium (resected papillary muscle) - under comparative conditions there was also found a similarity with the findings in the other two species with reference to myocardial pH. Instead of the uncertain determination of A T P in the human left ventricular m y o c a r d i u / n m u l t i p l e e l e c t r o n microscopic investigations were carried out. The results of these confirmed a relation between pH and metabolic state of the human heart similar to observations in the dog and calf. Institute of Physiology I, Universilty of G6ttingen D-34 G6ttingen, Humboldtallee 7

32 THE EFFECT OF TRANSIENT CARDIAC ARRESTCAUSED BY VAGUS STIMULATION ON THE OXYGEN SUPPLY TO THE DOG-MYOCARDIUM+. S. Schuchhordt, Th. Ryzlew|cz, Techn|sche AssTstenz I~ Chrlstof Intramyocardlal oxygen pressure (Po2) was measured in the anesthetized thoracotomlzed dog during stimulation of vagus. Tile right vagus nerve exposed at the neck was stimulated electrically for periods ranging from 2 sec. to 2 mln. When the time of cardiac arrest was long enough arterial blood pressure fell within 11 sec. (mean value) to a static value of about 30 mm Hg. The heart stopped maximally for 14-18 see., even though stimulation was continued. Always the heart started to beat spontaneously at a very slow rate. In the first phase of cardiac arrest (1 . - 1 0 . sec.) local tissue Pr~o Tn most cases decreased or remained unchanged. Sometimes it rose slightly. With stlm"u'tatlons of longer duration Pc~9 fell in all cases. The slope of decrease was very different. During the static phase of v ~ blood ~ressure meaa sJ.o~e v&lue amounte~ to 0,~6 To~r/se~,

Upon cessation of stimulation he~t frequency and blood pressure were quickly reestablished. Local POO did not show d unEorm course in the first reoxygenation phase, As a rule it took several" minutes to reach the pre-stTmulatlon level. - The results demonstrate, that aerobic metabolic balance ~ dog myocardium is not seriously impaired by cardiac arrest or severe bradycardla lastlngup to 2 minutes. Department of Physiology, Frele Universit'cit Berlin, 1 Berlin 33, Arnimallee 22 +Supported by Deutsche Forschungsgemelnschaft (Schu 174/3)

R17 33

THE CORONARY STEA~ PHENOMENON AFTER ADMINISTRATION OF VASODILATORS. U. Meyer, W. Schiffer and W.K. Raff The influence of several coronary dilating drugs on collateral blood flow was tested in 13 anaesthetized dogs. The anterior descending branch of the left coronary artery was ligated, cannulated and embolized by microspheres. The effect of coronary dilating drugs on antegrade and retrograde blood flow and pressure was measured. After intracoronary infusion of adenosine into the circumflex branch of the left coronar~ artery the retrograde blood flow decreases to 77,1 • 3,9 % of the original value. Under nitroglycerine the retrograde blood flow diminished to 86,2 • 2,2 %, under dipyridamol to 86,9 • 3,2 %, under carbochromen to 83,1 • 4 , 1 % and under nifedipine to 88~I • 1,2 %. From these results is concluded that vasodilating drugs improve coronary blood supply in the normal myocardium but decrease the blood supply to the area with insufficient blood supply. Physiologisches Institut I der Universit~t DGsseldorf D ~000 DGsseldorf, HoorenstraBe 5 ~

34 DIFFERING EFFECTS OF ACUTE AND PROTRACTED CORONARY OCCLUSION ON THE TIME COURSE OF THE VENTRICULAR FIBRILLATION THRESHOLD(VFT) OF THE HEART. H.GUlker, B.Kr~mer, K. Stephan and W.Meesmann in 26 piritramide-N20-a'n'aesth'e'ti'zed open chest d"olgms(17-24'"kg)ram. desc.art.cor.sin, was either ligated acutely (n=lS) or i t was constricted within 4-7 hours with a micrometer cuff occluder (n=8)in order to obtain for each dog a pass of the c r i t i c a l flow reduction without any acute haemodynamic changes. VFT was determined after acute ligation ( a . l i g . ) : every 2 min for 20 min, 30 min and then hourly up to 10 hours; in the cases of slow constriction: 5 min after each micrometer step. F i b r i l l a t i o n was induced by square wave current puls trains (140 ms). These were applied d i r e c t l y to the myocardium and p1~ced by R-wave triggering across the vulneraperiod of t~e cardiac cycle. After a. f i g . VFT dropped from H2 , , - 1 , 5 mA to I0-4,5 mA (p O,O01), The minimal current was measur between the 4th and 8th min. VFT then increased. 30 min after aJ~. praeocclusion VFTs were reached again. This change of VFT coincides with phase I of arrhythmias and its maximum incidence of spontaneous VF. VFT the remained stable uprto I0 hours, especially so during phase I I of arrhythmias beginning 4-6 hours post-infarction. In slow constriction ( t y p i c a l l y : no phase I of arrhythmias and no VF (Stephan and Meesmann:Verh.dtsch. Ges.Kreisl.Forsch.3g(lg73)208)) VFT is lowered ~or a few min+only on-passing the c r i t i c a l flow reduction from 17~1 mA to 13,5-1.5 mA (p
R 18 35 THE INTERSTITIAL pH OF THE CANINE MYOCARDIUM DURING ISCHEMIA* Hj. Hirche, P. Gaehtgens, C. Steinhagen, E. Schumacher and H.J. Kleine Measurements of th~ interstitial pH were performed in the canine myocardium using H sensitive bulb type glass minielec~rodes with a tip diameter of about I00~. Arterial and coronary sinus pH were measured continuously. Two side branches of the R. descendens and circumflexus of the left coronary artery were cannulated to measure local myocardial blood flow electromagnetically. One or two of the corresponding epicardial veins were also cannulated to obtain coronary venous blood from regions of the left ventricle during ischemia. Under normal conditions of flow and acid base balance arterial pH was 7-#, coronary venous pH was 7.36 and interstitial pH was 9.21. After clamping of one+or more side branches of the left coronary artery interstitial H activity increased within 5 minutes up to 215• per 1. After 30 min of arterial occlusion interstitial H~activities up to 6~0 nmoles per 1 were reached. The highest rates of interstitial H activity increases were 60 nmoles+per liter per minute. After release of the arterial occlusion H activities returned to control values within 2 - 4 minutes. Under normal conditions coronary venous base excess (BE) was more positive than arterial BE which is due to lactic acid oxidation. During ischemia coronary venous BE was more negative than arterial BE as consequence of LAproduction. Institut fGr normale und pathologische Physiologie der Universit~t zu K~ln, 5 KSln #1, Robert Koch Str. 39 *Supported by the Deutsche Forschungsgemeinschaft (Hi 137/7) 36 R E G I O N A L M Y O C A R D I A L B L O O D F L O W A T R E S T A N D D U R I N G E X E R C I S E IN L E F T "~ENTRICULAR H Y P E R T R O P H Y J. Holtz, E. B a s s s n g e , P. B a r d a n d W. v. R e s t o r f f R e g i o n a l m y o c a r d i a l b l o o d f l o w (RMBF) in dogs was m e a s u r e d in or= d e r to e ~ I n a t e the a d e q u a c y of s u b e n d o c a r d i a l p e r f u s i o n in se= lectivspressure induced left v e n t r i c u l a r h y p e r t r o p h y . At the. age of 8 w e e k s p u p p i e s w e r e t h o r a c o t o m i z e d and a s n u g l y fit= r i n g b a n d was p l a c e d a r o u n d the a s c e n d i n g aorta. At the age of one y e a r R M B F ~ m i c r o s p h e r s technique) and m y o c a r d i a l o x y g e n con= s u m p t i o n ( ~ 0 ~ ) w e r e s t u d i e d at rest and d u r i n g m o d e r a t e exercise. C o r o n a r y d i l a t o r y c a p a c i t y was q u a n t i f i e d b y p o s t o c c l u s i o n reao= tire h y p e r e m i a and b y d i p y r i d a m o l s . R e s u l t s 8 L e f t v e n t r i c u l a r w e i g h t w a s d o u b l e d c o m p a r e d to. C o n t r o l s ( l i t t e r m a t e s of same age). L e f t vent.,icular e n d d i a s t o l i c p r e s s u r e was not s i g n i f i c a n t = ly e l e v a t e d . At r e s t left v e n t r i c u l a r R M B F w a s 72 ~ 5 m l / I O O g . m i n and left v e n t r i c u l a r M SO 2 was 10.8 ~ 1.1 m l / l O O g - m i n . R e s p e c t i v e v a l u e s in c o n t r o l d o g s w e r e 66 ~ 6 and 9.8 ~ 1.0. S u b s n d o c a r d i a l R M B F w a s s i g n i f i c a n t l y h i g h e r t h a n s u b e p i c a r d i a l R M B F b o t h in c o n t r o l s and in h y p e r t r o p h y . T h i s t r a n s m u r a l g r a d i e n t in R M B F fa= r o u t i n g the s u b e n d o c a r d i u m r e m a i n e d u n c h a n g e d d u r i n g m o d e r a t e e x e r c i s e in c o n t r o l dogs, but d i s a p p e a r e d in the h y p e r t r o p h y group. R M B F m e a s u r e d u n d e r m a x i m a l c o r o n a r y d i l a t i o n was s i ~ n i f i = c a n t l y d i m i n i s h e d in h y p e r t r o p h y (per unit of tissue w e i g h t ) . The d a t a d e m o n s t r a t e a n o r m a l t r a n s m u r a l d i s t r i b u t i o n of m y o c a r d i a l b l o o d flow, but a r e d u c e d c o r o n a r y r e s e r v e for d i l a t i o n in the n o n - f a i l i n ~ h y p e r t r o p h i e d left v e n t r i c l e . Physiol.

Inst.

der Un~versit~t,

8 M ~ n c h e n 2, P e t t e n k o f e r s t r o

12

R~ 37 V A S O D I L A T O R Y C A P A C I T Y IN D I E F E R E N T LAYERS OF THE LEFT VENTRICLE H. Flohr, W. Breull, W.K. Raft, F.W, Schulz, D. Redel, H. Dahners The v a s o d i l a t o r y c a p a c i t y of the subepicardial, middle and subendocardial layers of the left ventricle was determined n anaesthe t i z e d mongrel dogs by (A) hypoxla- and (B) d l p y r i d a m o l e induced vasodilation. Regional blood flow was measured by labelled particles. With d i p y r l d a m o l e induced vasodilation the vascular resistance (mm Hg/ml/1OOg.min) decreased from a normal value of 1.42 ~ 0.15 S.E.M. to 0.37 ~ 0~05 in the subepicardial, 1.14 ~ 0.1 to 0.32 0.02 in the middle and 0,79 : 0,05 to 0.33 ~ 0,02 in the subendocardial layer. With hypoxia (SaO 2 < 5 0 % ) the PRUIo 0 decreased to 0.29 : 0.04 in § subepicardial, 0.25 Z 0,04 In the middle and 0.21 • 0.03 in the subendocardial layer. It follows that the v a $ o d i l a t o r y c a p a c i t y has its highest absolute value but -due to the transmural gradient in resting PRUIo O- its lowest relative value in the Subendocardia layer. Dept, of Physiology# University of Bonn, D 53 Bonn, Nussallee 11 and Dept. of PhysiOlogy, University of DUsseldorf, D 4 D~sseldorf, Moorenstrasse 5

38 T R A N S M U R A L D I S T R I B U T I O N OF BLOOD FLOW CANINE LEFT VENTRICEE W, Breullj S. Schuchhardt, H. Flohr

AND OXYGEN TENSION IN THE N. Niederle, A. Hoppe,

The transmural distribution of blood flow and oxygen tension was determined in the anterior left ventricular wall in 16 open chest

dogs. R e g i o n a l f l o w was measured by means o f l a b e l l e d p a r t i c l e s (H. F l o h r , P f l ~ g e r s A r c h . 3 0 2 : 2 6 8 , 1 9 6 8 ) ; oxygen t e n s i o n was det e r m i n e d with Pt n e e d l e - e l e c t r o d e s IS. Schuchhardt, Pfl~gers Arch. 32~:83, 1971). ~ith a mean arterial blood pressure of 103 ~ 5,5 S.E.M. mm Hg and a mean arterial oxygen partial pressure of 94 ~ 6.9 Tort flow To the subepicardial layer was 105 ~ 12.0 ml/1OOg,min and 97 ~ 10 to the subendocardial layer. In both layers PO 2 values ranged from 0-70 Torr and showed an asymmetrical frequency distribution with a maximum at 0-5 Tort. Mean tissue oxygen tension was I0.0 ~ 1.94 Tort in the subeplcardial and 12.3 ~ 1.8 in the subendocardlal layer. These values were not s i g n i f i c a n t l y d i f f e r e n t from each other. These results do not agree with previous investigations (cf. Molr, Th, Circulat. Res. 30:621, 1972) in which a transmura gradient In tissue oxygen tension with a lower PO 2 in the s u b e n d o c a r d i u m was shown. They are at variance with the hypothesis that the subendocardium is u n d e r p e r f u s e d under normal pressure flow conditions. (Honig, C.R. et al In: Coronary circulation p.31 Karger, Basel 1967). Dept. of Physiology, University of Bonn, D 53 Bonn, Nussa lee 11 and Max Planck Inst, f. S y s t e m p h y s i o l o g i e , D 46 Dortmund, Rheinlenddamm 12

R 20

3~ ANALYSIS OF THE COMPLEX EFFECTS OF INTRAAORTIC BALLOON PUMPING IN EXPERIMENTAL HEART FAILURE E.R. de Vivie, K. Hellberg, D. Kettler, G. Klaess, J. Koncz and H.J. Bretschneider Two animal studies were designed in order to analyze the multiple effects of the intraaortic balloon pump (IABP) on cardiac hemodynamics and coronary blood flow (coronary artery serial ligature, arterial hypoxemia after beta-adrenergic blockade). Severe cardiac depression was noted: systolic aortic blood pressure fell to 86~mHg left ventricular enddiastolic pressure rose to 14mmHg; mean pulmonary artery pressure was significantly encreased; dp/dt was lowered to approximately 50 % of control. Cardiac hemodynamics were temporarily during IABP treatment stabilized: calculated myocardial blood flow rose approximately 19 %. Arrhythmias were positively influenced and cardiac index was increased io % after 20 minutes Of IABP. The improvement of myocardial performance and energy balance was expressed by a significant fall of enddiastolic left ~entricular pressure (27 %) during the treatment period. Our experiments suggest that, due to the systolic unloading and diastolic augmentation, IABP-treatment can counteract the imbalance between myocardial energy demands and supply in cardiac failure. Since IABP increased myocardial blood flow to the right ventricle, it can be of benefit in right ventricular failure, too. IABP effects are less pronounced to severe arterial hypot~en~fon (systolic aortic pressure below 60mmHg) special emphasis is therefor laid on the early begin of IABP. Klinik f~r Thorax- und H e r z - G e f ~ c h i r u r g i e , Physiologisches Institut, Lehrstuhl I u n d institut fGr Klinische Anaesthesie der Universit~t G~ttingen, 34 G6ttingen. 4O VOLTAGE CLAMPED CAT VENTRICULAR CURRENT INT0 INWARD AND OUTWARD T.F. M c D o n a l d

MUSCLE: S E P A R A T I O N OF MEMBRANE COMPONENTS W. T r a u t w e i n and

A quantitative

measurement of the a m p l i t u d e of the slow i n w a r d c u r r e n t (ICa) a n d the time c o u r s e of its i n a c t i v a t i o n requires an a s s e s s m e n t of the t i m e - d e p e n d e n t outward current. This h a s b e e n a c c o m p l i s h e d b y a n a l y z i n g c u r r e n t r e c o r d s from 10 sec dep o l a r i z a t i o n s a n d r e l a t i n g the c o m p o n e n t s seen in these currents to u n d e r l y i n g c o n d u c t a n c e changes. C u r r e n t r e c o r d s from depolarizations to 0 mV c o u l d be fitted with 3 e x p o n e n t i a l s h a v i n g ~ 's of about 85, 360 a n d 3200 msec. R e l a t i v e amplitudes varied but were of the o r d e r 1.0, 0.4 and 0.2 respectively. Repolarization f r o m 0 b a c k to -60 mV resulted in predominantly inward tail curr e n t s at e a r l i e r t i m e s a n d o u t w a r d tails at later times. The inw a r d tail c u r r e n t e n v e l o p e ( c o n d u c t a n c e ) c o u l d be fitted with ~ = 85 m s e c w h i l e the o u t w a r d e n v e l o p e was d e s c r i b e d b y e = 300 mseo. The i n w a r d tail current amplitude was dependent on (Ca)o a n d was g r e a t e r at -90 than -60 mV. The outward tail current reversed at a b o u t -90 m V in 3 m M K + a n d -60 m V in 15 m M K +. T h e s e r e s u l t s s u g g e s t that the i n w a r d tails r e f l e c t e d gCa w h i l e the o u t w a r d tails r e f l e c t e d a gX" From long depolarizations it was found that Ica i n a c t i v a t e d with ~ ' s from 50 m s e c at -30 mY to 1 0 0 m s e c at +20 mY while I K ~ 's were about 500 m s e c at -20 m V a n d 300 m s e c at +20 mV.

II. Physiolegisches 6650

Homburg/Saar,

Institut W-Germany

der Universit~t

300 msec at -60 mV, des Saarlandes,

R 21 41

THE INFLUENCE OF STIMULATION FREQUENCY ON THE ACTIONPOTENTIAL DURATION OF GUINEA PIG'S PAPILLARY MUSCLE UNDER VARIOUS CONDITIONS A. Heueck, W. Ketel, and E. Rumberger Papillary muscles isolated from the right,ventricle of guinea pig's heart were stimulated electrically with various frequencies. Using microelectrode-technique actionpotentials (AP) were recorded. The dependence of duration of APs on stimulation frequency (in a range between 30 and 480 Imp/min) and the chan~e in duration following sudden changes in stimulation frequency (in the range of ~• to 3 octaves) were studied under various conditions of Ca-'-concentrations, temperature and sympathicomimetics (orciprenaline). Results: I. During steady state the duration of AP decreases exponentially with higher frequencies• The steepness of this relationship lessens with increasing Ca ~ - or orciprenaline-concentration. 2. After a sudden change in stimulation frequency new steady state duration of AP is achieved nearly exponentially within 100 to 200 beats. The a c h i e v m ~ t of new steady state duration is accelerated by increasingCa - or orciprenaline-concentration. 3. Alternating long- and shortl a s t i ~ APs after sudden rise in stimulation frequency are seen if Ca --concentration or temperature is lowered. According to these results the duration of the AP attains a new steady state after sudden change i~stimulation frequency in the manner of a damped oscillator. Ca ~ and sympathicomimetics increase damping. Institute of Physiology, University of Hamburg, 2 Hamburg 2G, Martinistr. 52 42 TIME COURSE OF TENSION CHANGE~ IN ~ I N E A PIG ATRIA FOLLOWING ALTERATION IN HEART RATE OR ~a~o J.J. Schulze and H.Ch. LGtt~au In guinea pig auricular trabecu4ae~ either heart rate or extracellular calcium concentration LCaJo was varied stepwise in a range where the dose response curves were nearly linear. A change of heart rate between 2 and 4 Hz or of ~C~ o between 0.9 and 2.7 mM induced tension changes, whose time course could be described by two exponential phases. These two phases could be observed in the time course of build up as well as in the decline of tension in response to enhancement or reduction of heart rate or ~ oThe changes of tension occurred parallel to those in maximum rate of tension rise. 68-77% of the tension change resulting from an altered heart rate could be attributed to the initial rapid phase (half-time between 1.2 and 2.4 sec; t=35oc). The later slow phase (half-time between 12 and 30 sec) accounted for the remaining 23-32% of tension change. A direct relationship existed between the magnitude of the two phases and the change of heart rate~ Th~ size of these phases rose linearly with an increased step in heart rate; the initial fast phase more steeply than the later slow phase. The variation of twitch tension under changed conditioas of heart rate or ~C~ o is interpreted on the basis of the hypothesis that contraction results from the cooperative interaction of two calcium compounds. A comparable hypothesis has been discussed by Chapman, R.A. and Niedergerke, R. (J. Physiol. 211~ 389-421 ~nd 432-443, 1970) for similar experiments on frog heart ventricle. Lehrstuhl Zellphysiologie,

Ruhr-Universit~t,

463 Bochum, Postfach

R 22 43

EFFECT OF E X T R A O E L L U L A R NA A N D K ON THE A C T I V E NA E F F L U X F R O M NA LOADE D CARDIAC CELLS H.G.Glitsch~ H. P u s c h and K. Venetz T h e relationship b e t w e e n extracellular Na or K concentration ( ~ N ~ ~; CK]~) and the active Na efflux was studied in guinea-pig auricles wish an increased intracellular N a concentra~ion(CNa~.). The p r e p a r a t i o n s were cooled for ~ h in a K poor s o l u t i o n in l order to augment CNa]~. A f t e r w a r d s the atria were rewarmed in solutions with various N a and K concentrations. The net N a transport during rewarming was calculated from measurements of the N a content, the water content and the extracellular space. Similarly, the Na i n f l u x d u r i n g recovery was derived from the g N a ~ variation in r e w a r m e d atria which h a d b e e n depleted of the io~ b y cooling in Na free media. The active N a efflux was then estimated from the data. The efflu~ from the auricles remained constant (at about 24 p m o l e s / c m "s or 3.2 mmoles/litre fibre water" min) in rewarming media with 1.55 m M K and O; 25; 50; 75 or I00 per cent of the n o r m a l 2 ( 1 4 9 mM) Na, while the N a influx increase~ from 4.4 p m o l e s / c m "s at 25 per cent K N a ] ~ to I0.3 pmoles/ cm~'s at I00 p e r cent [Na]^. R e w a r m i n g the atria in media with 0.4 m M K and various N a concentrations also y i e l d e d a constant active N a efflux and a N a influx which i n c r e a s e d w i t h E Na]_. However~ the active Na efflux from rewarmed auricles with ~ i g h KNa]~ was strongly dependent on g K]~. A s s u m i n g N i c h a e l i s - M e n t e n kinetics, the maximal K activated, ~ctive N a efflux was estimated to be about 28 p m o l e s / c m "s (3.7 mmoles/litre fibre water" min). The K activated N a efflux is half maximal at a g K 1 of 0.2 mM. o Lehrstuhl Zellphysiologie, R u h r - U n i v e r s i t ~ t Bochum, P o s t f a c h 2~48 44 D~ONSTRATION OF REENTRY WITHIN THE HIS-PURKINJE-SYSTE~ ~ IN MAN FleischmanntT.Po p and J.A.I. DeBakker

D.W.

in 28 patients without evidence for acute myocardial infarction theheginning of the relative refractory periods (RRP) of the His-Purkinjesystem (HPS) for antegrade and retrograde conduction and the effective refractory period (ERP) of the right ventricle were determined for different basic driving rates using the extrastimulus method and His bundle electrograms.Additionally,the retrograde intraventricular conduction time (CT) from the right ventricle to the bundle of His was measured.As exspeeted,the RHP of the His.Purkinje-system was significantly longer than the ERP of the right ventricle.As a result of this,the retrograde intraventrieular CT (100-350msec) increased with progressing prematurity of the ventricular extrastimulus,- In 48/28 cases a spontaneous premature ventricular heat ~P~C) or runs of PYC's were observed at critically delayed retrograde conduction times.Reentry within the His-Purkinje-system is postulated as an explanation for the spontaneous PVC1s. This hypothesis is based on the following: 1.The difference in the refractory periods between the HPS a=~ the ventricul&r myocardium. 2.A positive correlation between the duration of the retrograde intraventricular CT and the occurrence Of the PVC's. 3.The change of QRS morphology of the PVC's in cases with intraventricular conduction defects. 4. The demonstration of concealed retrograde oonduction intothe left bundle branch by premature right ventricular stimuli. Supported by DFG/SFB - 109 Abteilung I n h e r e Medizin I u n d Helmholtz I~stitut an der RWTH Aachen D 51 Aachen. G0ethestr. 27/29

R 23 45

DEMONSTRATION OF SUPERNORMA~ CONDUCTION IN THE HUMAN RIGHT ATRIUM T. Pop,D. Fleischmann and J.M.T. De Bakker A phase of supernorma! conduction within the human right atrium could be demonstrated in 4 of 13 patients during programed premature atrial stimulation studies.By recording the monophasic action potential within the right atrium the intraatrial conduction time (IACT) could be accurately measured. With progressive shortening of the premature beat interval 2 types of response of the IACT were observed.In 9 of 13 cases the IACT first remained Constant before showing a progressive lengthening untill the effective refractory period of the right atrium was reached.In the remaining 4 cases an unexpected shortening for 10 to 20 msec of the IACT could be demonstrated at the end of the full recovery time and before the begining of the relative refractory period of the right atrium which coincided with the final lengthening of the conduction time.This phenomenon is compatible with the so called supernormal phase of conduction. Supported by DFG/SFB-109. Abteilung Innere Medizin I und Helmholtz-Institut fur Biomedizinische Technik an der RWTH Aachen. D-51 Aachen Goethestrasse 27/29. 46 DIFFUSION DELAYS AND THE EATE OF CONTRAOTURE DEVELOPMENT IN FROG w~ART MUSCLE D.J. Miller In heart muscle, raising C ~ o or reducing [N~ o induces contractures which tend to develop slowly relative to the normal twitch or that under voltage clamp. It is important for the interpretation of the contracture data to know if this slowness is mainly due to a delay in the diffusion of the contracture medium or if contracture represents a fundamentally different type of activation. The rate of exchange of the extracell~lar space with the perfusing fluid in frog auricle trabeculae ~dia. c. I O 0 ~ ) was determined from the rate at which the twitches were abolished in 0 C a R i n g e r ' s (half-time 2-@ s which agrees with estimates by other methods, Chapman, 1971; Niedergerke & Page, 1972). It is known from previous experiments (Miller, 1975) that in 'zero' Na fluids half-maximal contracture occurs at pCa 6. The muscle was perfused with 'zero' Na Ringer's (pCa 7-5, 0.1 mH EGTA) for 30 s and then contracturewas induced by one of a series of pCa's from 5 to 1, which all activate maximally. If diffusion limits the rate o f tension development, the contracture should rise more rapidly at higher pCa's since the level necessary for 50% activation will be surpassed faster. The time to 50% activation was typically 5-6 s (pCa 5), 2-4 s (pCa 3)~ and 0.6-0.7 s (pCa I). The perfusion method itself limits further acceleration. The normal twitch and the fastest contracture develop at a similar rate at 10 ~ The results indicate that the rate of contracture development can be enhanced by a procedure which is expected to circumvent a part of any diffusion delay. Lehrstuhl Zellphysiologie,

Ruhr-Universit~t,

463 Bochum, Postfach

R 24

47 POSITIVE AND NEGATIVE INOTROPIC EFFECTS AS CONDITIONED BY THE TIME REQUIREMENT FOR THE DEVELOPMENT OF MAXIMAL CONTRACTILITY K1. Baumann In an appropriate cell a n d p r o t e i n free perfused left atrial preparation of guinea-pig with intact fibres, under optimal conditions of oxygen supply, pressure amplitudes of rhythmical contractions are highly influenced by perfusion time and at the later stages - also by rate of stimulation. Maximal contractility, in terms of pressure development during "testcontractions" elicited 2 to 4 sec after a series of rhythmical contractions, does not depend on perfusion time at higher stimulation rates. It is also not affected by negative or 6Positive inotropic agents (nifedipine 0.2 mg/1; noradrenaline 10- mol/1), inspite of strong effects on rhythmical contractions. Both findings are explained by the following facts: a) the amplitudes of testcontractions increase with the duration of resting-period, approaching highest values after 2 to 4 sec in an exponential manner b) the curve representing this relationship is steepened by noradrenaline and flattened by nifedipine particularly in the range of short testintervals, but in both cases rising to almost the same Ievel. It is concluded that noradrenaline accelerates, nifedipine delays the development of full contractility during resting-periods. Institute of Physiology, University of Hamburg, D 2 Hamburg 20, Martinistr. 52 48 THE EFFECT OF HEART RATE CHANGES ON RIGHT AND LEFT VENTRICULAR dP/dt max AT DIFFERENT INOTROPIC STATES. A STI~DYON ISOLATED CANINE HEARTS. ~. Hoppe, K.D. MOller, and H.D. Schmidt

An increase in heart rate leads to a rise in dP/dt max in the left ventricle. As has been shown in previous studies (PflOgers Arch. 335, RI4, 1972) this is also the case in the right ventricle. In canine heart-lung-preparations it has been tested, whether the inotropic effect of rate increase is dependent on the contractile state of the myocardium. At control contractility an increase of heart rate from 140 to 200/min causes only a slight rise in left ventricular dP/dt'max or is without any effect. The more the performance of the heart is reduced, the more the rise in dP/dt max is pronounced. The EDP, however, decreases at all inotropic states. When EDP is kept constant during the heart rate increase, dP/dt max rises quite markedly at all contractile states, the steepest rise being now obtained at control contractility. In the right ventricle similar results are found though the values show wide variation. The inotropic effect (percent rise of dP/dt max. fixed EDP) is the same in both ventricles at control contractility, but is stronger in the right ventricle, at reduced contractile state of the myocardium. Department of Physiology, Free University of Berlin, IOOO Berlin 33, Arnimallee 22, Germany.

R 25 49 C A R D I A C M U S C L E LENGTH AND S H O R T E N I N G V E L O C I T Y t J, SEGARRA D O M E N E C H R. M A R T I N E Z JORDA.,

J. SANTAFE OROZ AND A. QUINTANA.

Cardiac m u s c l e length and shortening v e l o c i t y has been w i d e l y stu~ died w i t h o u t a total e s t a b l i s h m e n t of the e x i s t e n c e of a direct r e l a t i o n s h i p b e t w e e n the two. In r e l a t i o n to this p r o b l e m a t i c we studied in 30 W i s t a r rats the influence of v e n t r i c u l a r volume inc r e m e n t s p r o d u c e d by the injection i.v. of 0,4~0,8~i,0 ml of phy~ siologic solution upon the hemodynamic constants: PTD, PVI (left ventricle) Ps, Pd (aortic), dp/dt systolic m a x i m u m and heart rate. The m y o c a r d i a l lengs after the v o l u m e charge and the subsequent h e m o d y n a m i c m o d i f i c a t i o n s , are e v a l u a t e d under normal c o n d i t i o n s and under beta b l o c k i n g agents and c a l c i u m antagonists. In normal C o n d i t i o n s the v e n t r i c u l a r volume increment is a c c o m p a n i e d by an increase in PTD, PVI, Ps. Pd. and dp/dt systolic m a x i m u m w i t h o u t heart rate variations. After the a d m i n i s t r a t i o n of P r o p r a n o l o l (0,6 mg/Kg) and Iproveratril (i,0 mg/Kg) the same injected volumes m o t i v a t e a greater increment in PTD, and dp/dt than in anterior c o n d i t i o n s ~ ( p ~ , 0 5 ) . The dp/dt v a r i a t i o n s are related m o r e d i r e c tly w i t h increments of Pd. than w i t h the augments of PTD (p<0,05). D i s c a r d e d in these studies was the possible p a r t i c i p a t i o n of reverse staircase p h e n o m e n o n that the rat possesses. D i s c u s s e d are the r e l a t i o n s b e t w e e n the F r a n k - S t a r l i n g m e c h a n i s m and the m y o c a r dial s h o r t e n i n v e l o c i t y . 5O ELECTRON M!CROSCOPIC FINDINGS IN ISOLATED GUINEA PIG'S MYOCARDIUM FOLLOWING DIELECTRIC BREAKDOWN OF THE MEMBRANE H. Homburger, J. A. Rossner and H. Antoni Isolated papillary muscles from the right ventricle of the guinea pig were used to study the influence of injurious DC-pulses on the ultrastructure. Condenser discharges (capacity I - 100 ~F; charg i n g voltage 1000 V) were applied to the preparations through the b a t h i n g fluid. Discharges of 1000 V from a capacity of I pF caused longlasting reversible d e p o l a r i z a t i o n accompanied by contracture. Under these conditions the u l t r a s t r u c t u r e of the myocardium remained unaltered. Impulses of higher energy (10 - 100 ~F; 1000 V) were followed by ~ r r e v e r s l b l e d e p o l a r i z a t i o n and extensive destruction of cell organelles. The follo'wing findings were obtained: cell swelling, m y o f i b r i l l a r contraction bands, cracking of myofilaments, swelling of mitochondria with unequal density of the matrix and disruption of the cristae, dehiscences of intercalated discs. Removal of calcium from the bathing medium prior to the current application prevented these ultras-tructural changes but could not inhibit depolarization. It is suggested that the ultrastructural alterations are induced by-highly increased calcium influx and calcium overload of the cell due to a loss of the selective permeability of the membrane. Department. of Physiology, University o~ Freiburg i.Br. and Department of Pathology, University of Heidelberg, D 78 Freiburg i. Br. Hermann-Herder-Str. 7

R 26 51 THE EFFECT OF ORGANIC Ca-ANTAGONISTS (VERAPAMIL. PRENYLAMINE) THE CALCIUM TRANSPORT SYSTEM IN ISOLATED MITOCHONDRIA OF RAT CARDIAC MUSCLE M. Frey and J. Janke

ON

r ............................................

The organic Ca-antagonistic compounds verapami! and prenylamine inhibit excitation-contraction coupling of heart muscle.by blocking the transmembrane Ca influx through the ',slow channel". The effective concentrations for a 50 % inhibition of contractile force of isolated rabbit papillary muscle are 0.0002 n~M verapamil or 0.0045 mM prenylamine. Complete suppression of contractility could be obtained with O.OO2 mM verapamil or O,O15 ~ prenylamine. In this concentration range verapamil and prenylamine have no effect on mitochondrial Ca uptake or release. T o produce a 50 % inhibition of net Ca uptake a verapamil concentration as high as I mM is required. Prenylamine (0.02 raM) exerts the same effect.In contrast to the verapamil or prenylamine actions on the cardiac sarcolemma membrane, the mitochondrial effects of these drugs can neither be washed out nor overcome by high Ca concentrations in the incubation medium. Furthermore it could be shown that I m M verapamil or 0.02 mM prenylamine increase the rate of spontaneous Ca release from Ca-loaded mitochondria probably because the mitochondrial membranes become leaky. The present data show that t h e negative-inotropic doses of verapamil, w h i c h interfere with the Ca influx through the "slow channel", amount to only 1/50OO of those which affect the transmembrane Ca movements on the mitochondria. Therefore, the reversible depression of contractility produced by small amounts of verapamil or prenylamine cannot be attributed to the alterations in the mitochondrial Ca metabolism. Physiological Institute, University of Freiburg, Germany 52 CHANGES OF SLOW INWARD CURRENTAND CONTRACTIONAT LOW EXTRACELLULARpH IN MAMMALIAN VENTRICULARMYOCARDIUM. M.Kohlhardt, Kp. Haap an4 H.-R. F i g u l l a In order to analyze the pH dependence of the slow membrane channel and resuitant changes of e x c i t a t i o n - c o n t r a c t i o n coupling, Ca action p o t e n t i a l s were e l i c i t e d a f t e r i n a c t i v a t i o n of the fast Na system in p a p i l l a r y muscles of cats using K-rich (15 mM) Tyrode s o l u t i o n . At a pH of 5.5 a decrease of upstroke v e l o c i t y occurred w i t h i n t0 minwhich amounted to 23 r on an average. The action potential duration was diminished by 11 ~.. Resting p o t e n t i a l and overshoot remained unchangedo A f t e r a longer time of exposure to the acidmedium in some cases a recovery of upstroke v e l o c i t y appeared. ~ On the other hand, c o n t r a c t i l e a c t i v i t y declined continuously and a f t e r 25 min a 63 r decrease was obtained. Acidosis did not prevent the normal response of the slow membrane channel towards excess Ca (4 mM) of isoproterenol (1 mg/1). In both cases the usual .increase of upstroke v e l o c i t y of C@ action potentlal and of cont r a c t i l e force occurred, Apart from,the reduction of the upstroke v e l o c i t y acidosis d r a s t i c a l l y prolonged the r e f r a c t o r y period of the Ca action potential. Obviously, acidosis causes a d d i t i o n a l l y a deceleration o f recovery from inact i v a t i o n of the s,low membrane channel which may be also caused by an acidosisinduced reduction o f f i x e d negative charges. Excess Ca (4 mM) normalyzed the time course of recovery. The results show that the negative inotropic e f f e c t of acidosis is not s t r i c t l y c o r r e ] l a t e d to a proportional change in Ca current suggesting that the reduction in c o n t r a c t i l e force must mainly be a t t r i b u t e d to changes at intrace|iular reaction sites, Physiological I n s t i t u t e of the U n i v e r s i t y , Freiburg/Bro, Hermann-Herder-Str.7

R 27

53

THE INFLUENCE OF ALKALOSIS UPON Ca CURRENT AND CONTRACTION IN MAMMALIAN VENTRICULAR MYOCARDIUM. Kp. Haap and M. Kohlhardt I t is well-known that alkalosis produces a positive inotropic effect in heart muscle. In order to clarify whether this effect is mediated by an enhanced transmembrane Ca influx the influence of alkalosis upon the Ca-mediated action potential was studied in papillary muscles. Ca action potentials were elicited after inactivation of the fast Na system using K-rich (15 mM) Tyrode solution. At a pH of 7.8 producedby reduction of the CO2 concentration (simulating respiratory alkalosis) an augmentation of upstroke velocity of the Ca action potential by 26 % and a 32 % increase of contractile force occurred. Resting potential, action potential duration and refractory period of the Ca system remained unaffected. In view of this relatively slight increase in Ca conductance the D 600-induced blockade of the slow channel could not be overcome by alkalosis. I f the pHwas elevated to 7.8 by an increase of bicarbonate ,(simulatin~ metabolic alkalosis) nearly the same quantitative response of contractile activity appeared. However, no increase of upstroke velocity of t h e Ca action potential could be found; there was even a diminution of 15 %. The results show that only "respiratory" alka!osis promotes Ca conductanceof the membrane. This indicates that the positive inotropic effect of "metabolic" alkalosis depends upon mechanismsother than enhancement of transmembrane Ca influx during excitation. Probably an intracellular pH effect on the contractile system i t s e l f is responsible for the increase in contractile activity. Physiological Institute of the University, Freiburg/Br., Hermann-Herder-Str. 7 54 INTERACTIONS OF CARDIAC GLYCOSIDES AND Ca-ANTAGONISTIC DRUGS WITH EXCITATION-C0NTRACTION COUPLING IN ISOLATED CORONARY SMOOTH MUSCLE K. Naka[ama r Y.K. B[on and G . F l e c k e n s t e i n - G r ~ n Helical coronary strips prepared from pigs and rabbits strongly respond to cardiac glycosides. With a concentration as small as 10 ~g/l k-str0phanthin in the bathing fluid, resting tension of rabbit coronary strips is nearly doubled whilst isometric tension, developed upon electric stimulation, is increased by 150 % (alternating square wave impulses of 10 V/cm, 10 Hz and 18 sec.duration). This effective dose for coronary strips is only 1/80 of that required on rabbit papillary muscles for the production of maximum ~sometric tension (800 ~g/l k-strophanthin). Thus, coronary smooth muscles appear to be more susceptible to cardiac glycosides than the myocardium. The profound coronary action of cardiac glycosides can be effectively eliminated by administration of small amounts of Ca-antagonistic compounds (verapamil, D 600, nifedipine) without a major reduction of the glycoside-induced inotropism on the myocardium. Contractility and tone of electrically stimulated coronary strips can only be maintained in the presence of extracellular Ca. 0bviously~ cardiac glycosides facilitate the transmembrane Ca supply to the contractile system so that an enormous sensitization of coronary smooth muscle to extracellular Ca takes place. Ca-antagonistic compounds act in the opposite sense. Physiological

Institute, University of Freiburg,

Germany

R 28

55 INFLUENCE OF EXCESS Ca AND HYPEROSMOTIC SOLUTIONS ON TENSION DEVELOPMENT IN RESTING AND STIMULATED CORONARY SMOOTH MUSCLE DIFFERENTIATION BETWEEN 2 FORMS OF CONTRACTILE ACTIVATION Y. K. B~on and K. Nakay ama .... -

Coronary strips (pig, rabbit) were exposed to Tyrode solution (a) with different Ca contents and (b) with additional sucrose. With increasing Ca concentration, isometric tension development upon electric stimulation was progressively augmented. At a Ca concentration between 8 and 10 mM/l the contractile responses r e ~ ched a maximum, consisting of a 3-fold increase above the original level at 2 mM/l. With Ca concentrations higher than 10 mM/l, however, isometric tension development was precipitously diminished whereas a further rise in resting tension took place. Ca-antagonistic compounds abolish the effects of additional Ca on contractile force and resting tone. A similar disappearance of the m e c h ~ nical responses to stimulation with concomitant elevation of resting tension could also be produced at a normal Ca content by administration of a hyperosmotic solution (twice normal osmolarity). But in contrast to the effects of high Ca concentrations the hyperosmotic augmentation of basal tone proved to be resistant against Ca-antagonistic compounds and persisted even in a Ca-free hyperosmotic solution. The results indicate that changes in resting or active tension development of coronary smooth muscle, produced at normal osmolarity, depend on the transmembrane supply of extracellular Ca, whereas in the case of contractile activation by hyperosmolarity Ca is probably delivered from intracellular stores. Physiological

Institute,

56 CALCIUM-SODIUM ANTAGONISM H. G. Haas and R. Kern

University

of Freiburg,

ON THE FROG'S HEART

Germany

(I)

In double sucrose gap voltage clamped frog atrial fibres the influence of ~a~ o a n d ~ o on tonic (sustained) contractions during p r o l o n g e G depolarizations was tested. With moderate changes in ~ a ~ o and ~ _ ~ o 2 t o n i c contraction was quantitatively defined by the ~ S ~ o / ~ N ~ o ratio at any level of depolarization. With extensive changes in ~ o , the negative inotropic effect of external N a was smaller than expected from the ~ a ~ o / ~ ~ ratio, No correlation between steady tension and steady state current was found. The results are tentatively explained in terms of a voltage-dependent but electroneutral carrier mechanism exchanging one Ca for two Na ions across the cell membrane. This system is thought to operate close to equilibrium at any membrane potential, thus determining the steady level of myoplasmic Ca, but the equilibrium itself will be shifted by deoolarization. This would result in a continuous increase Of ~ i with increasing membrane potential. A sudden depolarization may cause a transient inward transfer of Ca into the myoplasm persisting until the n ~ (increased) steady level o f ~ i is reached. Provided that~ i is constant, the steadx_level of~myoplasmia Ca is expected to be proportional to t h e ~ o / ~ a ~ ratio, the scale factor being a function of membrane potential. ~y combining the voltage clamp data with biochemical data (Winegrad, 1971) the kinetics of the carrier system can be described in quantitative terms. Department of Physiology II, University of Bonn, Wilhelmstr.31, D 53 Bonn

R 29 57

CALCIUM-SODIUM ANTAGONISM ON THE FROG'S HEART (II) H.M.Einw~chter and G.Brommundt In further voltage clamp experiments on frog atrial fibres the sensitivity of slow (secondary) inward c ~ < e n t and phasic (transient) contraction to changes in ~aJo a n d W ~ o was studied. At a given depolarization slow inward current varied with ~ o but was almost unaltered by changes i n ~ o- In contrast, phasic contraction associated with slow inward current was affected by either ion. At moderate depolarizations phasic contraction followed the ~ a ] o / ~ ~ ratio rather closely. The ~ositive inotropic effect of an increase i n ~ o or a decrease i n ~ o was manifested by an increased dP/dt and a prolonged time to peak tension. Because of the a~pparent irresponsiveness of slow inward current to changes in LNaJo this current seems unlikely to form the molecular basis of Ca-Na antagonism. As an alternative explanation, the antagonistic effects of external Ca and Na are interpreted in terms of a transmembrane Ca-Na exchange mechanism responsible for Ca extrusion from the fibre. In this view the positive inotropic effect of an i n c r e a s e d ~ o o r a decreased~ o is related to a rise of the resting level o f ~ i and a slowed rate of Ca extrusion. Department of Physiology II, University of Bonn, Wilhelmstr. D 55 Bonn

51

58

EFFECT OF HISTA},{INE ON ELECTRICAL AND ~{ECHA}TICAL ACTIVITY IN 9ROG ATRIL9~ R. Kern and [,K. Lindner In frog atria, the influence of histamine I0-7Z on action potential, membrane current, and contraction was studied, using the double-sucrose-gap technique. Histamine caused a marked increase in upstroke velocity, and a decrease in amplitude and duration of the AP; the effective refractory period was shortened. Voltage clamp measurements showed a 200 %-increase of peak transient (Na ~) current. The rates of sodium activation (m) and inactivation (h) were accelerated, the curve relating steady-state availability of Na current to membrane potential was shifted by 7 mV to more positive potentials. The increase of sodium current must be contributed 9o the acceleration of m. The slow (secondary) inward current was suppressed, ~ the phasic (twitch) contraction, related to this low (Ca)current, was decreased. The tonic (sustained) contraction, in contrast, was markedly increased. Under the influence of histamine the sodium content of the fibres was increased; so the increase of the tonic contraction may be explained by a model for the Na2/Ca-antagonism: the amplitude of the tonic contraction depends on the Naand Ca-content outside, and the Na-concentration inside the fibre.

Department of Physiology I, University of Heidelberg, D-69 Heidelberg, Im Neuenheimer Feld 526

R 30

59 SOME ASPECTS OF THE RELATION BETWEEN THE CURRENT UNDERLYING PACE MAKER ACTIVITY AND BETA ADRENERGIC RECEPTORS IN CARDIAC PURKINJE FIBRES * K.Hashimoto *,0.Hauswirth and R.Ziskoven * It has been previously shown that adrenaline(A)shifts the relation between the steady state degree of activation of the pacemaker current and the membrane IPctential ( s ~ as well as the reciprocal of the time c o n s t a n t ( ~ ) in the dep~larizing direction and that the beta receptor blocking agents pronethalol and propranolol restored the kinetics back tq their original position.(Hauswirth et al.1968,Science,162,916,Tsien, 1974 a,b,J.gen.Physiol.64,293 ff) The question arose w-~ther this back shift is due to a be'~a receptor blockade or to a pharmacological effect by its own, i.e. the local anaesthetic side effect of the beta adrenergic blocking substances used so far.Voltage clamp experiments have been done in order to answer this question:After the administration of A which caused the usual shift of the kinetics in the depolarizing direction procain up to 2.10-4g/ml did not shift the kinetics back Thereafter,in the presence of 5A a n d procaine,the beta receptor blocking agent ICI 66082 (10- g/ml)was added;the kinetics were n o w shifted back in the negative direction although not entirely to their original position.The instantaneous current voltage relation iK2 was altered by neither of the drugs used.The results exclude the possibility that the local anaesthetic side effect of the beta adrenergic receptor blockers m a y be responsible for the back shift of the s,kinetics. Department of Physiology II,University of Bonn,Wilhelmstrasse 31, 53 Bonn,Germany. 9 supported by the Deutsche Forschungsgemeinschaft, H a 850/2/3. 60 DEVELOPMENT OF A CROSSCORRELATION METHOD FOR THE CONTINUOUS RECORDING OF ARTERIAL PULSE WAVE TRANSMISSION Th. Kenner The transmission of pulse waves in the arterial system is influenced by reflections and damping, dependent on viscoelastic properties of the arterial wall. The interaction of these factors determine the magnitude of the phase velocities of the harmonic components of the pulse waves as well as the amplitudes of these components. In order to examine this problem, methods were developed ]) to continuously record the pressure transmission function and 2)to continuously measure and record the velocity of the wave front and the phase velocities of the pulse waves. The continuous measurement of the phase velocity of lower harmonics of pulse waves is accomplished by crosscorrelation of two trains of pulses and calculationof the lag time of the maximum of the crosscorrelatiqn function. If the crosscorralation function is 9#iculated after~differentiatlon of the pulses, an estimate of the phase velocity of higher harmonics can be calculated. The average speed of the method is one crosscorrelation and, therefore, one velocity value each 10 pulse periods. The calculations are performed on line on a Hewlett Packard 2]OO A computer. For the evaluation of the method the relation between phase velocities and the velocities estimated by the crosscorrelation method was examined theoretically and expe~imentally. Supported by Osterreichischer Ponds zur FSrderung der wissenschaftlichen Forschung Physiologisches Institut, Universit~t Graz, A-80]O Graz, Mozartgasse 14

R81 61 CO~[PARISON OF DIFFERENT METHODS FOR THE CONTINUOUS MEASUR~[ENT OF THE PULSE WAVE VELOCITY E. David, Th. Kenner, H.PeBenhofer and G. Schwaberger Two principles can be used for the continuous recording of the puls wave velocity: |) The measurment of the time lag between two characteristic points at the front of the pulse wave. 2) The evaluation of the crosscorrelation function. A more general application of the first method is impeded by several problems which are related to the difficulty to find reproducible trigger levels~ and to the great sensitivity to external noise. In order to find corresponding measuring levels, furthermore, the pulses have to be scaled. The crosscorrelation method, on the other hand, has the advantage of being independent of trigger levels. Due to the averaging property of the correlation methods the influence of noise and body movements is rather small~ The method does not need any scaling of the pulses. For the evaluation of the two methods experiments were performed in rabbits, rats, and cats. The results were compared with measurements on human being. It was found that the wave velocity measured with the new method t e n ~ to be higher than the front velocity, especially during vasoconstriciton. Both values are strongly dependent on the arterial pressure. Supported by ~sterreichischer Fonds zur FSrderung der wissenschaftlichen Forschung l. Physiologisches Institut, Universit~t Erlangen, D-852 Erlangen, Universit~tsstraBe |7 Physiologisches Institut, Universit~t Graz, A-80|O Graz, Mozartgasse |4 62 E S T I M A T I O N OF T H E P H A S E A N G L E OF THE PERIPHERAL R E F L E C T I O N COEFFICIENT IN THE ARTERIAL S Y S T ~ Y.Summa, RiD,Bauer , and R.Busse The peripheral reflection coefficient can be calculated from the complex characteristic impedance of a supplying artery and the complex input impedance of the resistance vessels. The latter can be simulated by a series of longitudinal resistors and transverse capacitors terminated b y a transverse resistor ( R O C K ~ A N N 1965 and 1971). Although the reflection coefficient is, in principle, complex, it is often assumed to be real for the purpose of approximation calculations. This means that its phase angle is considered to be zero. As a contribution to the resolution of this problem, a calculation of sign and magnitude of'the phase angle was carried out in the frequency range of haemodynamic interest. The basic data such as vessel diameter, wall thickness, v i s c o s i t y of fluid and wall, compliance etc., were taken from the literature. The results are discussed with respect to the phase relationship b e t w e e n arterial pressure and flow as well as to those peripheral r e f l e c t i o n coefficients which should be applied in analog and digital models of the arterial system. References: R~ckemann, ~., Habil.-Schrift, Frankfurt a.Main 1965. RSckemann, W., G . C o n r a d and H.Luther, 6th Europ.Conf.Microcirculation, Aalborg 1970, pp. 259-262, (Karger, Basel 1971). Institut fGr P h y s i o l o g i e u n d Kardiologie der Universit~t, D-8520 Erlangen, Waldstrasse 6

R 32 63 HORMONAL CONTROL O~ DYNAMIC ELASTIC MODULUS AND LOCAL PLOW IMPEDANCE OF LARGE CANINE ARTERIES E.Monos, R.H. Cox and L.H. Peterson Changes in dynamic elastic modulus and local blood flow impedance of canine common carotid and femoral arteries during topical as well as systemic arginine-vasopressin administration /30-150 /uE/ml blood/ have been studied i_Bnsit~ before and after hypophysectomy. A decrease in carotid and femoral elastic mcduli /25-35, and 17-24 per cent respectively/ and in local flow impedances /I0-17, and lO-18 per cent/ for the first to fifth Fourier harmonics was found one to two hours after hypophysectomy. Vasopressin applied topically /intraluminally at stop flow/ did not influence the carotid elastic modulus significantly, but did reduce femoral modulus by 22-26 per cent before, and by 21-25 per cent after hypophysectomy~ Vasopressin administered intravenously increased elastic moduli and local impedances in both arteries; the effects were enhanced after hypophysectomyo It is concluded that vasopmessin in concentrations within endogenous limits significantlyinflusnces the in vivo elasticity of arteries. Experimental Research Department, Semmelweis Medical University, 1082 Budapest, Ull6i ut 78/a 64 D E T E R M I N A T I O N OF C E L L U L A R AND P L A S M A T I C F L O W V E L O C I T Y IN V I T R O AND IN VIVO. P. Gaehtgens, K.U. Benner, S. Schickendantz, and K.H. A l b r e c h t Red cell fiow v e l o c i t i e s were m e a s u r e d in glass capillaries ( d i a m e t e ~ 9 - 42 ~m) and in m e s e n t e r i c m i c r o v e s s e l s of the rat using the p h o t o m e t r i c dual slit technique. Two additional photosensors were emploYed to record signals caused by the passage of a bolus of Evans Blue (5 g%) injected into the flowing blood. Average p l a s m a flow velocity was calculated f r o m t h e d e l a y o b s e r v e d between c o r r e s p o n d i n g signals. The separation b e t w e e n the photosensors r e c o r d i n g dye p a s s a g e was 950~m referred to the level of the g l a s s c a p i l l a r y ; in the intravital m e a s u r e m e n t s this separation was v a r i e d according to the m i c r o v a s c u l a r geometry. The dual slit separation c o r r e s p o n d e d to a distance of 11.5 ~ in vitro and to 3.4 ~m in vivo. In all e x p e r i m e n t s the ratio between the v e l o c i t y of the cells and of the plasma was larger than 1.0. In the smallest glass capillaries an average ratio of 1.86 was observed i n d e p e n d e n t l y of the absolute cell v e l o c i t y w h i c h varied b e t w e e n I and 25 mm/sec. In the m i c r o v e s s e l s (diameter 6 - 15 ~m) the flow v e l o c i t y varied between 0.2 and 1.5 mm/sec. Institute for Normal and P a t h o l o g i c a l K61n, 5 K~in 41, Robert-Koch-Str. 39

Physiology,

University

of

R33 65

ULTRASONIC TRANSIT-TIME TECHNIQUE FOR RECORDING OF ARTERIAL DIAMETER PULSATIONS AND ITS APPLICATION IN H A ~ O D Y N A M I C S G.Heinlein, R.D.Bauer, R.Busse, H.Fuchs, and Th.Pasch Two piezo-electric crystals (Sonox 2, diam. 4 mm, 0.3 mm thick), coated with aluminium powder in epoxy, were glued to the opposite sides of a s u r g i c a l l y exposed artery (cf. Aars, Bertram). The emitter crystal is excited by impulses (35 V, 1/us) at a repetition rate of 25,000/s and gives off a burst of ~ltrasonic waves at each impulse. In addition, each impulse sets a flipflop. The sound impinges upon the receiver crystal with a delay equal to the sound transit time between the two crystals, thus generating an electric signal which resets the flip-flop. In this way the flip-flop produces a 25 kHz train of square-wave voltage signals, each of which has a length equal to the respective sound transit time. The mean voltage of the square-wave signals, obtained by low-pass filtering with an upper frequency limit of 500 Hz, is proportional to the transit time and thus to the diameter of the vessel. The method was applied to the ascending aorta of rabbits and to the femoral artery of dogs. Combined with simultaneous intra-arterial pressure recordings and other measurements, it was used for the determination of arterial dynamic elasticity and characteristic impedance. References: Aars, H., Acta physiol, scand. 75, 597-#05, 1969; Bertram, C.D., J. Physiol. 241, 85P-87P, 1974. Institut f~r Physiologie und Kardiologie D-8520 Erlangen, Waldstrasse 6

der Unlversit~t,

66 THE EFFECT OF CHANGING TRIGGER SIGNAL / STIMULATION R-WAVE TRIGGERED CAROTID SINUS NERVE STIMULATION T. Peters, R. Daube and E. Zerbst

RATIOS IN

In anaesthetized spontaneous breathing mongrel dogs the effect of R-Wave triggered electrical carotid sinus nerve stimulation (CSNS) was studied, varying the trigger signal / stimulation ratio by means of a gate circuit. With the applied ratios of i:i to 1:8 the intervals between two consecutive impulse trains (i0 imP/train , imp. duration I ms, train duration i00 ms) ranged from one to eight heart cycles. Thus the lowest average impulse frequency was reached by coupling the impulse train to every ninth R-Wave. In another series of experiments this feed back loop was interrupted by applying a pacemaker which elicited a constant heart rate despite of any effect of previous or actual CSNS. In stimulation with 1 heart cycle interval the maximal normalized drop in systol~ic bloodpressure (Ps) was 40 %, in diastolic pressure (Pd) 48 %. Heart rate dropped by 16 %. With 8 heart cycles interval time Ps was lowered by 13 %, Pd by 16 % and heart rate by 6,6 %. In pacemaker experiments corresponding values are: Ps 24 %, Pd 3 1 % for the shortest interval and Ps 9 %, Pd i0 % for the longest interval of stimulus trains. Supported by Stiftung Volkswagenwerk g e m e i n s c h a f t (Ze 67/7). Institut f~r Physiologie, FU-Berlin,

and Deutsche Forschungs1 Berlin 33, Arnimallee

22

R34 67 INFLUENCE OF FREQUENCY AND PULSE WIDTH IN ELECTRICAL CAROTID SINUS NERVE STIMULATION R. Daube, C. Borst, J.M. Karemaker, J. Wagner, A.J. Dunning and E. Zerbst In 3 anginal and 3 hypertensive patients carotid sinus nerve stimulation (CSNS) was applied during periods of 90 seconds'using a modified angistat stimulator (Medtronic Inc). Stimulation pulse width was either 0.35 or 2.0 ms and the frequency ranged between 20 and IOO Hz. In the anginal patients the largest reduction of arterial blood p r e s s u r e , pulse pressure and heart rate was obtained with 80 - iOO Hz, 0,3 ms stimulation. In the hypertensive patients the optimal combination between frequency and pulse width differed considerably from patient to patient. In 9 normotensive nembutal anaesthetized mongrel dogs CSNS was applied with variing stimulation frequency (2 - 120 Hz) and pulse width (0,i - 3,0 ms) to get more informations about the most effective stimulation parameters in animal experiments. The influence of CSNS on heart rate, respiratory rate and systemic blood pressure has been studied. CSNS was applied via platinum iridium electrodes bilaterally. In some of the dogs the heart rate was fixed with a cardiac pacemaker. In general the largest reduction of heart rate and blood pressure was obtained with higher stimulation frequencies and shorter impulse width. In a few dogs the most effective pattern varied with time and sometimes lower frequencies and larger impulse width have been most effective. Supported by Deutsche Forsch. Gem. (Ze 76/7) and Stilt. VW-Werk. Institut fur Physiologie, FU-Berlin,~ 1 Berlin 33, Arnimallee 22 Jan Swammerdam Institut,University of Amsterdam,Huygensstraat 20. Med.Klinik,Cardiol.Abt.,Univ.Bonn,Bonn-Bad Godesberg,Venublerg 68 ELECTRONIC CLOSED LOOP CONTROL OF THE CARDIOVASCULAR SYSTEM AND oF ARTIFICIAL MECHANICAL HEART PERFORMANCE E~ Zerbst, K.-H. Dittberner, R. Daube, J. Wagner and M. Schaldach Arterial blood pressure and ventricular pressure excite baroreceptors which in turn influence sympathetic and parasympathetic networks of cardiovascular regulation. An electronic baroreceptor analog - with input-output characteristic of natural baroreceptors has been applied as blood pressure and heart rate controlled carotid sinus nerve stimulator in patients in angina pectoris and hypertension. Results of comparative 24 h control and 24 h stimulation studies (telemetric registration of bloodpressure and heart rate) are demonstrated. Responsitivity to electrical carotid.sinus nerve stimulation is best in the evening period and less sensitive in the morning and at midday. - The application of the electronic receptor analog is possible in the control of artificial mechanical heart performance. The advantage is the delivery of natural shaped blood pressure pulses adopted to the heart rate, which in turn is controlled by means of an electronic "center". Technical principles and control mechanisms and the electronic setup of the analog system to be used are demonstrated. -

Supported by Stiftung Volkswagenwerk and Deutsche Forschungsgemeinschaft (Ze 67/7). Institut fur Physiologie, FU-Berlin, IO00 Berlin 33, Arnimallee 22 Kardiologische Abteilung Med. Universit~tsklinik Bonn, BonnVenusberg Dept. Biomed. Technik, Universit~t Erlangen.

R 35 69 REDISTRIBUTI?N OF MICROCIR~ULATION A NEW2PRINCIPLE OFIREGULATION. B. A. Krtunme , R. Strehlau-, K. Sch6nleben , M. Kessler -

Hydrogen clearance curves were recorded to determine microflow in the liver in situ under the conditions of normoxia and hypoxic hypoxia. We used multiwire surface electrodes, the platintun wires of which were palladinized using a modification of L~bbers's and Baumg~rtl's method: Very pure palladium chloride was dissolved in O , 1 M hydrochloric acid, heated and stirred electromagnetically. A ring shaped platinum anode was fixed around the multiwire electrode during palladinizing with a current of I/uA for 4 minutes. The gas mixtures with which the animal were respirated consisted of either 20 % or iO % oxygen in nitrogen and included 10 % hydrogen during saturation. During the experiments the Po 2 was registered simultaneously on the liver surface as a control parameter oE physiological conditions. The values of relative microflow indicate that an inhomogeneous patternof microcirculation exists in the tissue. The highest flow rates found are more than IOO % higher than the lowest values. When hypoxic hypoxia was induced we found a characteristic change in the distribution of microflow. The highest values decreased by 2 3 , 1 % of their original values, while those of the intermediate flow groups decrease by 17,4 % and those of the low group by only 13,2 %. This observation seems to confirm the assumption that a redistribution of microcirculation occurs in hypoxia in a similar way in rat liver as in the dog liver (Kessler, M., Microvasc. Res. ~, 283 (1974). I) Max-Planck-lnstitut fO/ Systemphysiologie, D-46 Dortmund, Rheinlanddamm 201 2) Chirurgische Universit~tsklinik, D-44 M~nster, Jungeblodtplatz i

70 P R O P E R T I E S OF A N U N I D E N T I F I E D N O N D I A L Y Z A B L E V A S O P R E S S O R F A C T O R H U M A N S E R U M A N D P L A S M A H.Wurm, H.Dowertil, E~Zierlerand Th.Kenner

IN

I n c u b a t i o n of h u m a n p l a s m a or s e r u m at 37~ i n d u c e s {he g e n e r a t i o n of a n o n d i a l y z a b l e v a s o a c t i v e f a c t o r ( c a l l e d A P P b y K e n n e r & W a l d h~usl, Z.Kreislaufforschg. 58, 1 1 4 3 , 1 9 6 5 and V A by C r o x a t t o & Diaz, Proc. Soc. Exp. B i o l . M e d . ] 3 0 , 4 6 5 , ] 9 6 9 ) . The goal of this s t u d y w a s to e x a m i n e the p r o p e r t i e s of this f a c t o r in o r d e r to find an indication of its p o s s i b l e p h y s i o l o g i c a l role. A f t e r i n c u b a t i o n at 37~ for m o r e t h a n 24 h o u r s the i . v . l n j e c t l o n of 0, I m l / l O 0 g h u m a n s e r u m in a n e s t h i z e d r a ~ p r o d u c e s a short (I min) p r e s s u r e i n c r e a s e up to 50 m m Hg, due to v a s o c o n s t r i c t i o n . S e r u m f r o m h y p e r t o n i $ or blnephrectomized p a t i e n t s shows no d i f f e r e n c e c o m p a r e d to n o r m a l c o n t r o l s . Sera f r o m o t h e r m a m m a l s (horse, hog, ox, r a b b i t , g u i n e a pig, rat) p r o d u c e s i m i l a r , but w e a k e r e f f e c t s a b o u t 20 m m Hg. The v a s o p r e s s o r e f f e c t of The same dose is m u c h less p r o n o u n c e d in g u i n e a pigs. In cats the i n t a v e n o u s i n j e c t i o n of 0 , 0 2 m l / l O 0 g l e a d s to a t r a n s i e n t b r a d y c a r d i a and b l o o d p r e s s u r e fall a b o u t 50 m m Hg. In r a b b i t s d o s e s of 0, I m l / l O 0 g p r o d u c e o n l y a s l i g h t fall in b l o o d p r e s s u r e . The u n k n o w n f a c t o r is f o u n d in the a l b u m i n f r a c t i o n , its g e n e r a t i o n can be i n h i b i t e d by e n z y m e b l o c k e r s . The s p e e d of g e n e r a t i o n is h i g h e s t in s l i g h t a l k a l i n e m i l i e u . In the rat the e f f e c t s are not m e a s u r a b l y i n f l u e n c e d by a l p h a - or h e r a b l o c k i n g a g e n t s . P r e t r e a t m e n t of the a n i m a l s w i t h r e s e r p i n e does not a l t e r t h e b l o o d p r e s s u r e r e s p o n s e . APP seems to be a h i g h l y a c t i v e s u b s t a n c e the p h y s i o l o g i c r o l e of w h i c h w i l l be u n c l e a r u n t i l the m e c h a n i s m of a c t i o n can be e s t i m a t e d . S u p p o r t e d by the A u s t r i a n H e a r t Fund, P r o j e c t 202 Physiologisches I n s t i t u t , Univ. Graz, A - 8 0 1 0 Graz, M o z a r t g a s s e 14

8 36

71 ANAPHYLACTIC

SHOCK IS NOT HISTAMINE

SHOCK.

K. Pavek

The aim of, the study was to identify mediators potentially responsible for circulatory shock in anaphylaxis (a.). Anaphylactic shock was induced in p r e s e n s i t i Z e ~ m a c a c a monkeys by~ insertion of albumin. A low cardic output and systemic arterial hypotension ensued with slow recovery in nonfatal cases in about 1 hour. Peripheral vascular dilatation and decreased heart filling and venous return were usually accompanied by!acute pulmonary hypertension and occasionally by ventricular arrhythmias, ischemic ST-T changes and/or a left-right asymmetriC: pump failure. Premedication with a prostaglandin synthetaselnhibitor indomethacin, 5 mg/kg, did not prevent these changes. Peripheral vascular collapse could he corrected by dextran. Infusion of a SRS-S antagonist prevented the development of anaphylactic shock. Instead, an increase in systemic~ pulmonary artery and venous pressures occurred, suggesting release of catecholamines. Injections of histamine, prostaglandins Eg, P~o alone or in combination did not imitate the hemodynamic evefits ld a.shock. Histamine or PGE 2 induced arterial hypotension but increased cardiac output. HiStamine o r PGFgo resulted in pulmonary hypertension hut PGF~a alone did not chw the cardiac output. Injection of compoun~ 48/80, a histamine and probably SRS-A liberator, increased initially cardiac output but later the hemodynamic events were closely similar to those in a. shock. The results of this model study suggest that SRS-A is a more important mediator in the circulatory shock due to a. than histamine and prostaglandins. Dept.of Diagnostic Radiology,Univ.Hosp.and Pharmacia AB,Uppsala/S. 72

~EXPERIMENTS ON THE SIGNIFICANGE OF THE SOCALLED APPARENT INPUT IM?EDANCE FOR THE DESCRIPTION OF CORONARY PRESSURE-FLOW RELATION K. Pascale and Th. Kenner The input ~mpedance of an artery is defined as quotient of complex input pressure and flow. Due to the rhythmic squeezing of the myocardium the features of the coronary input impedance show certain peculiarities which make the analytical definition of a linear input impedance impossible. For this reason we have used the expression apparent input impedance (Kenner,Pfl~gers Arch.310,22,1969).The question has to be examined whether the calculation of an impedance under these premises is useful at all. The main reason for the difficulties of a linear description is the nonlinearity introduced by the action of the aortic values which, physiologically, is essential for the normal pressure-flow relation. In order to examine the features of the apparent input impedance the coronary flow was recorded in anesthetized dogs and the impedance values were calculated. The results were compared with experiments in two models of the coronary arteries: I) an airchamber model and 2)a transmission line model wSth time varying outflow resistance. We could show that the results of both models is very good. The apparent input impedance is not a continuous function but a matrix harmonic values. We could show, furthermore, that the construction of a simple pressure-flow diagram provides information which can be interpreted and analyzed easier than the computed impedance, the interpretation of which has to be based on a non existing linearity of the system. Supported by ~sterr. Fonds zur FSrderung der wissenschaftl.Forschung Physiologisches Institut, Universlt~t Graz, A-8010 Graz, Mozartgasse ] 4

R 37

73 THE INFLUENCE OF CORONARY STENOSIS AND AORTIC PRESSURE ON CORONARY FLOW, CORONARY PRESSURE AND REACTIVE HYPEREMIA R.H. Wirth, W. Dietze, U. Mittmann and J. Schmier In previous experiments it was noted, that coronary flow and coronary pressure decreased significantly, when the coronary arterial diameter was reduced by 85 percent (K.L. Gould, Am. J. Cardiol. 34, 48, 1974). In our studies the total coronary arterial diameter is reduced by 50, 60, 70, 80 and 90 percent by a micrometer constrictor. For each degree of stenosis mean aortic pressure is maintained at a level of 60, 80, 100 and 140 mm Hg by means of a Windkessel. In 6 anesthetized shepherd dogs the following parameters are measured: coronary flow, poststenotic coronary pressure, reactive hyperemia after total occlusion of the coronary vessel for 10 seconds, aortic pressure and central venous pressure. When mean aortic pressure is 140 mm Hg coronary flow and poststenotic coronary pressure decrease significantly at a coronary stenosis of 90 % ( p < 0.001). With an aortic pressure of 100 or 80 mm Hg cgronary flow and pressure decrease at an 80 % stenosis (p< 0.01). At an aortic pressure of 60 mm Hg the decrease occur, when the stenosis is 70 % ( p / 0 . 0 5 ) . Reactive hyperemia, however, is significantly diminished b y a 60 % stenosis on each level of aortic pressure (p < O.05).Coronary perfusion pressure is an important parameter when defining 'critical' coronary stenosis. Abteilung fGr Experimentelle Chirurgie, t~tsklinik Heidelberg, D 6 9 H e i d e l b e r g ,

Chirurgische Universi~ Im Neuenheimer Feld 547

74 FURTHER IMPROVEMENT OF 02 MICROSENSOR STUDIES IN THE BRAIN +j H. Metzger and S. Heuber Results of 02 microsensor measurements from numerous points of the brain tissue have been plotted as PO 2 frequency distributions (histograms) by many authors. Basic presumption for histogram plot is invariability of the PO 2 values related to time. According to our observations in the brain tissue of albino rats (Wistar), time-independent PO 2 values are rarely to be seen. When pushing a microelectrode forewards perpendicular to the brain surface in~ steps of 10 microns, three types of PO 2 registrations can roughly be differentiated: a) almost constant PO 2 values with a stepwise PO 2 decrease after each electrode movement; observations from the upper layers within O - 200 microns from the brain surface. b) PO oscillations of O - 20 mmHg, mean value 5 - 25 mmHg; within 10~ - 500 microns distance from the brain surface, c) PO 2 at zero level; within deep regions of the brain. We conclude from our analysis that presumptions for histogram plot are not!fulfilled in many cases. In order to improve information gathered with a microsensor (tip diameter: 2-5 microns) in a tremendous tissue volume of some milliliters, simultaneous action potential and PO 2 and alternatively membrane potential measurements with the same tip of the gold electrode have been performed by an improved microelectronic equipment. +)Supported by-DFG Department of Physiology , Medizinische Hochschule Hannover, D 3 Hannover, Karl-Wiechert-Allee 9

R38 75 REGULATION

OF PIAL ARTERIOLAR

DIAMETERS

E. Betz and M. Csornai By m e a n s of perivascular microperfusion of pial arterioles and small p i a l a r t e r i e s in c a t s t h e e f f e c t s of i n t e r a c t i o n s of H + and C a ++ and K+ and C a ++ w e r e i n v e s t i g a t e d . It w a s d e m o n s t r a t e d that i n c r e a s i n g H + o r K + in t h e p e r i v a s c u l a r s p a c e i n h i b i t e d t h e c o n s t r i c t o r y a c t i o n of p e r i v a s c u l a r C a ++. A d d i t i o n of 2 . 5 m m o l / L N o r a d r e n a l i n o r 2 . 5 m m o l / L S e r o t o n i n to t h e p e r i v a s c u l a r C S F c a u s e d v a s c u l a r c o n s t r i c t i o n w h i c h c o u l d be i n h i b i t e d by p e r i v a s c u l a r a c i d o s i s o r s t r o n g p e r i v a s c u l a r a l k a l o s i s (which p e r s e l e a d s to c o n s t r i c t i o n ) . W i t h E G T A a l l m e n t i o n e d c o n s t r i c t o r y e f f e c t s c o u l d b e o v e r r u l e d . T h e r e s u l t s d e m o n s t r a t e t h e c e n t r a l r o l e of C a ++ in t h e r e g u l a t i o n of p i a l v a s c u l a r d i a m e t e r and t h e d e p e n d e n c e of t h e t r a n s m i t t e r - e f f e c t s on the ionic p e r i v a s c u l a r m i l i e u . P h y s i o l . I n s t . I, U n i v e r s i t ~ t TUbingen, D 7400 T ~ b i n g e n , G m e l i n s t r . 5 76 CEREBRAL BLOOD FLOWAND OXYGENSUPPLY DURINGVENTRICULAR-CISTERNALPERFUSION J. Grote, R. Schubert and A. Fenske The s u r v i v a l chances during b r a i n l e s i o n s are s i g n i f i c a n t l y a f f e c t e d by the magnitude of the r e s u l t i n g b r a i n edema which p r e c i p i t a t e s t i s s u e hypoxia and l a c t a t e a c i d o s i s . Due to r e c e n t evidence t h a t b r a i n edema development can be advantageously i n f l u e n c e d by high flow r a t e p e r f u s i o n of the l i q u o r system, we l e ve lop ed a p e r f u s i o n technique which allows an exchange of the v e n t r i c u l a r l i q u o r 15 times per hour w i t h o u t ICP i n c r e a s e . The o b j e c t of our i n v e s t i g a t i o n was t o show t h a t the high flow r a t e p e r f u s i o n of the v e n t r i c u l a r system of normal b r a i n has no d e l e t e r i o u s consequences f o r c e r e b r a l 02 supply. The i n v e s t i g a t i o n was conducted on 18 c a t s a r t i f i c i a l l y v e n t i l a t e d under p e n t o b a r b i t a l a n a e s t h e s i a . The p e r f u s i o n was accomplished a f t e r s t e r e o - o p e r a t i v e c a n n u l a t i o n of the r i g h t l a t e r a l v e n t r i c l e and of the c i s t e r n a magnao The flow r a t e was 1.2 - 1.5 ml/min, PC02 of t h e a r t i f i c i a l l i q u o r was kept a t 30 and 55 mmHg. rCBF of the c o r t e x as w e l l as rCBF o f ar eas cvn%aining gray and white m a t t e r of the p e r f u s e d hemisphere was determined using the 85 Krmethod and the 133 Xe-method r e s p e c t i v e l y . Simultaneously the r e s p i r a t o r y gas p a r t i a l p r e s s u r e s , pH and l a c t a t e and pyruvate c o n c e n t r a t i o n s i n a r t e r i a l blood, in venous blood of the b r a i n and in the l i q u o r were determined. P e r f u s i o n over s e v e r a l hours of the v e n t r i c u l a r system produced no change in 0~ supply condit i o n s i n the i n v e s t i g a t e d b r a i n t i s s u e . Throughout, rCBF i n t h e - r i g h t f r o n t a l lobe c o r t e x ranged between 9 0 - 105 ml/lO0g min while CMR0~ remained a t a mean min r e s p e c t i of 8.5 ml/lOOg min. Mean values of 20 ml/lOOgmin and 2~ ml/lOOg z rely were observed in the brain areas containing primarily white matter. ICP remained constant during the experimen%s~ no edema occurred. Departments of Physiology and Neurosurgery, U n i v e r s i t y of Mainz, D 65 Mainz

R 39

77 CI~ITICAL LIMITS O F T H E O ~ C O N S U M P T I O N OF THE L I V E R +) J. Lutz a H. -G. Schulze m and E. Bauereisen

PERFUSED

In e x p e r i m e n t s on c a t s the 0 2 supply of the in ,Situ p e r f u s e d l i v e r was r e d u c e d i n e q u a l s t e p s down to v e r y low l e v e l s . O~ c o n s u m p t i o n d e c r e a s e d b e l o w 90 % of the n o r m a l v a l u e (5.90 + . 49 m l O ~ [ m i n 100 g l i v e r ) a l r e a d y at an 0 2 s u p p l y l e s s than 10 m l O 2 ] r a i n 100 g. ]in this c a s e 0 2 e x t r a c t i o n r a t i o did n o t s u r p a s s : 60 % though the m a x i I n a l 0 2 e x t r a c t i o n r a t i o of the l i v e r a m o u n t s to m o r e than 95 %. The O 2 c o n s u m p t i o n r e m a i n e d c o n s t a n t o n l y at an O~ supply h i g h e r than 10 m l O 2 / m i n 100 g while the 0 2 e x t r a c t i o n r a t i o r e a c h e ~ l o w e r v a l u e s . At r e d u c t i o n of O 2 s u p p l y the 02 e x t r a c t i o n r a t i o i n c r e a s e d but when it r e a c h e d v a l u e s of 85 % the O2 c o n s u m p t i o n had f a l l e n n e a r l y by half. A !!splay" a p p e a r e d in the d i a g r a m of the r e l a t i o n b e t w e e n the v e n o u s O 2 outflow and the O~ s u p p l y as well a s i n the r e l a t i o n of O 2 c o n s u m p t i o n v e r s u s 0 2 s u p p l y . W i ~ o u t ' , s p l a y " O 2 c o n s u m p t i o n should r e m a i n c o n s t a n t u n t i l O2 Supply d e c r e a s e d to 6 . 3 m l O 2 / m i n 100 g w h e r e b y the O2 e x t r a c t i o n r a t i o would i n c r e a s e up to 95 %. T h e r e a f t e r O 2 c o n s u m p t i o n would d r o p i m m e d i a t e l y b e l o w the l i n e "O 2 c o n s u m p t i o n = O2supply". The a p p e a r a n c e of a s p l a y s e e m s to b e , c a u s e d by the d i f f e r e n t length of s i n u s o i d s thus d e p e n d i n g r a t h e r on d i f f e r e n t O 2 l e v e l s than on i n h o m o g e n i t i e s of l i v e r c e l l s . The c u r v e of O 2 c o n s u m p t i o n plotted v e r s u s pO 2 showed that O2 c o n s u m p t i o n b e g a n to d e c r e a s e when the v e n o u s pO 2 f e l l below 25 - 30 m m Hg. P h y s i o l o g i s c h e s I n s t i t u t U n i v e r s i t ~ t D 87 Wiirzburga R 6 n t g e n r i n g 9 +) Supported b y a g r a n t of the D e u t s c h e F o r s c h u n g s g e m e i n s c h a f t 78 DILATORY RESPONSES TO A C E T Y L C H O L I N E IN THE INTESTINAL VASCULAR BED OF THE R A T M . D . Kababgi and H. H e n r i c h A c e t y l c h o l i n e (Ach) m a y e i t h e r dilate o r c o n s t r i c t v a s c u l a r s m o o t h m u s c l e ; s u c h an opposite b e h a v I o u r i s d e p e n d e n t upon the dose a p p l i e d o r the r e a c t i n g v a s c u l a r bed u s e d . Not too m u c h i s known about the u n d e r l y i n g m e c h a n i s m s as w e l l as the i n t e r a c t i o n b e t w e e n Ach and n o r a d r e n a l i n e (NA). In an i s o l a t e d s m a l l gut p r e p a r a t i o n we c o m p a r e d the effect of t e m p e r a t u r e c h a n g e s ( f r o m 37 ~ to 17~ on the N A - i n d u c e d v a s c u l a r tone and the A c h - c a u s e d v a s o d i l a t i o n . The c o n s t r i c t o r y effect of NA (1.25 ~ g / m l ) and the d i l a t o r y effect of Ach ( 0 . 0 2 6 , u g / m l ) w e r e f~und to be o p t i m a l at 32 ~ continuously decreasing with l o w e r t e m p e r a t u r e s . The d o s e - r e s p o n s e c u r v e of Ach showed an optim u m at 1 0 - 7 g ] m l , s i g n i f i c a n t l y d e c r e a s i n g with l o w e r ( 1 0 " g g / m l ) and h i g h e r c o n c e n t r a t i o n s ( 1 0 - 4 g / m l Ach) at a c o n s t a n t N A - c o n s t r i c t i o n . V a r y i n g the NAc o n c e n t r a t i o n (0.026 ~ug/ml) the d i l a t o r y effect of Ach p r o v e d to be d e p e n d e n t upon the p r e e x i s t i n g N A - t o n e p o i n t i n g to a c l o s e i n t e r a c t i o n b e t w e e n the two a g e n t s . C o m p a r i n g the d i l a t o r y r e s p o n s e s to Ach of a N A - c o n s t r i c t e d one with those of an e q u i e f f e c t i v e l y K C l - a c t i v a t e d v a s c u l a r bed r e s u l t e d in a s m a l l v a s o d i l a t i o n i n the l a t t e r g r o u p . To g e t s o m e i n f o r m a t i o n about a p o s s i b l e i n v o l v e m e n t of c a l c i u m , w e r e d u c e d ~a++]o f r o m 3.31 to 0.825 m M and s a w a s i g n i f i c a n t d i m i n u t i o n of the d i l a t o r y r e s p o n s e to Ach. U s i n g the C a - a n t a g o n i s t v e r a p a m i l (10 -9 to 1 0 - 6 g / m l ) w e o b s e r v e d a c o m p a r a b l e effect. U n d e r both c o n d i t i o n s the N A - i n d u c e d tone b e h a v e d in a s i m i l a r m a n n e r , but in a d i f f e r e n t with r e g a r d to the Ach-effeCt. We c o n c l u d e t h e r e is a N A - A c h i n t e r a c t i o n and c a l c i u m i o n s m i g h t play s o m e r o l e i n it. P h y s ~ o l o g i s c h e s I n s t i t u t d e r Universit~[t :D - 87 W i i r z b u r g , R S n t g e n r i n g 9

R 40 79 CORRELATIONS CENTAL BLOOD

B E T W E E N T H E N U M B E R OF U T E R O P L A C E N T A L A R T E R I E S , P L A FLOW AND FETAL GROWTH W. M o l l a n d E.M. P f 6 r r i n g e r

The b l o o d f l o w a c r o s s the h e m o c h o r i a l p l a c e n t a e is n o t l i m i t e d b y the r e s i s t a n c e of the t r o p h o b l a s t i c l a c u n a e b u t b y the r e s i s t a n c e of the u t e r o p l a c e n t a l a r t e r i e s (MOLL and K U N Z E L , 1971). The n a r r o w e s t s e c t i o n s of the u t e r o p l a c e n t a l a r t e r i e s in g u i n e a p i g s are ~ the r a d i a l a r t e r i e s . B e s i d e s t h e i r l u m e n and t h e i r length, the n u m b e r of r a d i a l a r t e r i e s m a y be an i m p o r t a n t f a c t o r for p l a c e n t a l b l o o d f l o w and p o s s i b l y for f e t a l g r o w t h . T h e r e f o r e , we t r i e d to e s t a b l i s h c o r r e l a t i o n s b e t w e e n the n u m b e r of a r t e r i e s , f l o w and growth. In p r e g n a n t g u i n e a p i g s n e a r t e r m p l a s t o i d c a s t s (SCHUMMER, 1951) and x - r a y p h o t o g r a p h s of t h e u t e r o p l a c e n t a l vascular system were made; the n u m b e r of r a d i a l a r t e r i e s s u p p l y i n g the d i f f e r e n t p l a c e n t a e w e r e d e t e r m i n e d . T h e d i s t r i b u t i o n of the p l a c e n t a l b l o o d f l o w on the p l a c e n t a e w a s m e a s u r e d w i t h J - 1 3 1 - a l b u m i n m a c r o a g g r e g a t e s (FLOHR, 1968) and the w e i g h t of the f e t u s e s w e r e d e t e r m i n e d . It w a s f o u n d (I) p l a c e n t a l b l o o d f l o w as p e r c e n t a g e of the a v e r a g e p l a c e n t a l b l o o d f l o w is c o r r e l a t e d w i t h the n u m b e r of r a d i a l art e r i e s p e r p l a c e n t a (y=54+18x; r = 0 . 5 ) , (2) f e t a l w e i g h t as p e r c e n tage of the m e a n is c o r r e l a t e d w i t h p l a c e n t a l b l o o d f l o w as exp r e s s e d a b o v e ( y = 5 2 + O , 4 8 x ; r=0.8) and, c o n s e q u e n t l y (3) f e t a l w e i g h t is c o r r e l a t e d w i t h the n u m b e r of r a d i a l a r t e r i e s p e r p l a c e n ta (y=75+12x; r = O . 5 ) . T h e r e s u l t s s u g g e s t t h a t the n u m b e r of r a d i a l a r t e r i e s per p l a c e n t a is of s i g n i f i c a n c e for p l a c e n t a l b l o o d f l o w and f e t a l w e i g h t . Institut

f~r P h y s i o l o g i e

der Universit~t

D-84

Regensburg,

Postfach

80 TISSUE 0XYGE~ SUPPLY OF.SKELETAL MUSCLE.AND LIVER AFTER.COBALT RADIATION. _ I J . , z 1 B. A. Krumme , J. H6per , K. Sch6nleben , 0. Fzschedlck , M. Kessler High oxygen levels in tissue increase the cellular vulnerability to energyrich rays, whereas anoxia diminishes the sensitivity to radiation. In a series of experiments with rats, the influence of cobalt radiation on local oxygen supply of skeletal muscle was investigated. Two groups of animals were treated seperately, the first group with a radiation dosage of 50 R and the second group with 5OO R. The local oxygen supply of muscle tissue was measured with multiwire Po2-electrodes. One hour after radiation, the Po2-histograms of the first collective showed a shift to a higher level. In the second group, an initial decrease of local Po 2 was observed. This was followed by a continuous increase up to an overshoot in the fourth hour after radiation. The potassium efflux caused by ischemia was investigated with ionselective potassium electrodes (Kessler, M., H6per, J., Simon, W., Fed. Proc. 33, 279 (1974). After radiation with 5OO R and a subsequent ischemia of ten minutes' duration the extracellularpotassitun activity increased by 1,6 mMol whereas an increase of only 0,39 mMol was observed after radiation with 50 R. First measurements in the liver in sftu showed that the redistribution of microcirculation, induced by hypoxic hypoxia, cannot be disturbed by radiation with 30OR. i) Max-Planck-lnstitut for Systemphysiologie, D-46 Dortmund, Rheinlanddamm 201 2) Knappschaftskrankenhaus, D-46 Dortmund, Wieckesweg 27 3) Chirurgische Universit~tsklinik, D-44 MGnster, Jungeblodtplatz I

R41 81

FACTORS DETERMINING THE PULSE CONTOURS OF THE DISTAL LEG ARTERIES OF MAN R.Busse, R.D.Bauer, Th.Pasch, Y.Summa, and E.Wetterer The normal pressure pulses of the distal leg arteries of man and of many animals are characterized by a sharp fall after the systolic maximum and a diastolic elevation, the so-called dicrotic hump, while the flow pulses exhibit a systolic forward flow followed by a phase of backflow and a further phase of forward flow. Although it is commonly agreed that the dicrotic pressure hump and the backflow phase are caused by reflected waves, the sites and modes of reflection of these waves are not yet clear. In order to elucidate these phenomena, we recorded pressure and flow pulses of human leg arteries transcutaneously and the corresponding pulses in the dog by intra-arterial manometers and ~ F measurement, under normal and artificially changed conditions. The peripheral wave reflection was e l i m l n a t e d b y strong vasodilatatlon in the distal region of both legs. From the result it was concluded that, under normal conditions, peripheral positive reflections of the original pulse wave in the end region of the lower legs, and negative reflections of the retrograde pulse wave, particularly in the abdominal aorta, are the main prerequisites for the genesis of the characteristic contours of the pressure and flow pulses of the leg arteries. This mechanism was simulated by a theoretical model using a digital computer. Institut f ~ r P h y s i o l o g i e und Kardiologle der Universit~t, D-8520 Erlangen, Waldstrasse 6 82 LOCAL REGULATION OF CAT SARTORIUS MUSCLE

BLOOD FLOW H. Henrich

STUDIED IN CAPILLARIES and P. C. Johnson

OF

Using the dual-slit photometric method (WAYLAND and JOHNSON, J. Appl. Physiol. 22, 333j 1967) red cell velocity profiles were obtained. We saw two different groups of capillaries with dissimilar reactive hyperemia patterns and a different extent of autoregulation. Changing the perfusion pressure stepwise from 60 to 150 mm Hg and performing 30 sec occlusions was followed in the strongly autoregulated group by an increasing peak to control flow ratio, whereas excess flow and time to peak flow remained unaltered. All the hyperemia patterns with an high initial flow increase and succeeding flow cessationj regarded by BURTON and JOHNSON (Amer. J. Physiol. 223, 517, 1972) as a myogenic behaviour of postoeclusive reactions, belonged to this group of vessels. The short and constant time to peak flow concomitant with good autoregalalion suggests a major involvement of myogenic mechanisms~ too. A pressure dependent increase of post-occlusion excess flow~ a shortening of the absolutely long time to peak flow and hyperernia duration were found in the second group of vessels~ which showed a weaker autoregulation. The hyperemia patterns of these capillaries were similar to those interpreted by BURTON and JOHNSON as mainly caused by metabolic factors. These vessels represented apparently a majority. We conclude that in skeletal muscle myogenic local regulation exists, however~ it is covered by metabolic influences. Physiologisehes Institut der Universit~t D - 87 W ii r z b u r g j Rbntgenring Dept. of Physiologyj Arizona Medical Center, Tucson, Ariz. 85724j USA

9

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83 P U L M O N A R Y P R E S S U R E - F L O W R E L A T I O N S H I P A F T E R T R A U M A AND HEMORRHAGE: THE E F F E C T O F I N T R A V A S C U L A R COAGULATION, ACIDOSIS AND P L A T E L E T AGGREGATION. H. L e i n b e r g e r , U. B. B r i i c k n e r , T h . K16ss, M. M e t z k e r , W. , S a g g a u and J. S c h r n i e r Due to a v e r y d i s t e n s i b l e p u l m o n a r y v a s c u l a r b e d , c a l c u l a t e d p u l m o n a r y v a s c u l a r r e s i s t a n c e i s e x t r e m e l y s e n s i t i v e to a l t e r a t i o n s of flow in low flow s t a t e s . T h e r e f o r e p u l m o n a r y v a s c u l a r r e s i s t a n c e i s not a s u i t a b l e p a r a m e t e r to g e t e v i d e n c e of p u l m o n a r y v a s o m o t i o n in shock. Using a s h o c k m o d e l with a s t a n d a r d i z e d bone t r a u m a f o l l o w e d b y s t e p w i s e h e m o r r h a g e to 40 m m H g and a s t e p w i s e r e i n f u s i o n a f t e r 3 h o u r s , two d i f f e r e n t p r e s s u r e - f l o w - r e l a t i o n c u r v e s ( P F C ) a r e o b t a i n e d by r e p e a t e d m e a s u r e m e n t s of c a r d i a c output and p u l m o n a r y a r t e r i a l and w e d g e p r e s s u r e s . T h e P F C a r e p l o t t e d f o r h e m o r r h a g e and r e i n f u s i o n p e r i o d s of e a c h e x p e r i m e n t . The s h i f t of m e a n p u l m o n a r y a r t e r y p r e s s u r e ( ~ M P P ) w h i c h i s d e t e r m i n e d f r o m the P F C at a flow of 100 m l / k g " m i n i s t a k e n as a quantitative measure for pulmonary vascular constriction or obstruction. T h e e x p e r i m e n t s w e r e p e r f o r m e d in 35 a n e s t h e t i z e d dogs. In c o n t r o l d o g s (n=10) ~ M P P i s 6 . 4 + 2 . 7 m m H g . H e p a r i n pretreatment(n=8) and T R I S - b u f f e r i n g (n=9) r e d u c e s /% M P P i n s i g n i f i c a n t l y to 4 . 3 + 2 . 3 m m H g and to 4.4-+2.8 m m H g r e s p e c t i v e l y . P r e t r e a t m e n t with a c e t y l - s a l i c y l i c a c i d and D i p y r i d a m o l e (n=8) r e d u c e s / % M P P to 3.0-+1.7 m m H g (p ~ 0 . 0 1 ) . It i s c o n c l u d e d t h a t T R I S - b u f f e r i n g and H e p a r i n p r e t r e a t m e n t a r e of m i n o r i m p o r t a n c e f o r p u l m o n a r y h e m o d y n a m i c s in shock. A b t e i l u n g fiir E x p e r i m e n t e l l e C h i r u r g i e , C h i r u r g i s c h e U n i v e r s i t f i t s k l i n i k H e i d e l b e r g , D - 6 9 H e i d e l b e r g , I m N e u e n h e i m e r F e l d 347 84 T H O R A C I C DUCT F L O W IN C O N S C I O U S AND A N E S T H E T I Z E D D O G S D U R I N G LARGE S A L I N E INFUSIONS. H. Schad, H. B r e c h t e l s b a u e r and K. Kramer C o n t i n o u s m e a s u r e m e n t of t h o r a c i c duct l y m p h f l o w r e v e a l e d a definite r e d u c t i o n d u r i n g anesthesia. Since b l o o d volume d e c r e a s e d s l i g h t l y imbalance of c a p i l l a r y f i l t r a t i o n and l y m p h a t i c return due to i m m o b i l i s a t i o n was c o n c l u d e d (Schad et al., P f l ~ g e r s Arch. 355:R22, 1975) In the p r e s e n t e x p e r i m e n t s in conscious dogs with large saline i n f u s i o n s t h o r a c i c duct flow i n c r e a s e d up to 6 times. P l a s m a volume rather increased. Evidently, dogs in conscious state are able to k e e p in b a l a n c e w i t h large infusions as also is demonst r a t e d by the e q u i l i b r i u m of i n f u S i o n and renal excretion. During a n e s t h e s i a t h o r a c i c d u c t flow was s t r o n g l y r e d u c e d while the augm e n t e d c a p i l l a r y filtration seemed to be unchanged. In c o n s e q u e n ce the plasma v o l u m e decreased. In a d d i t i o n renal e x c r e t i o n of s o d i u m and w a t e r became d i m i n i s h e d i n d i c a t i n g that renal function is d i s t u r b e d when lymphatic return is affected. The a s s u m p t i o n of K E C K et a l . ( P f l ~ g e r s Arch. 341 : 51 - 62, 1973) that p l a s m a fluid loss into the e x t r a v a s c u l a r space is the m a i n cause of sod i u m r e t e n t i o n can be confirmed. However, the u n d e r l y i n g m e c h a n i s m is rather a reduced l y m p h a t i c return due to i m m o b i l i s a t i o n d u r i n g a n e s t h e s i a than an i n c r e a s e d c a p i l l a r y permeability.

D e p a r t m e n t of Physiology, U n i v e r s i t y of Munich, P e t t e n k o f e r s t r . 12, Fed. Rep. Ger.

8 M ~ n c h e n 2,

R 43

85

ORIGIN, DISTRIBUTION AND TRANSPORT OF CELLULAR ENZYMES IN LYMPH R. Bode~ R. Friedel and I. Trautschold To elucidate the importance of the lymphatic system for a quantitative diagnosis of cell injuries by means of enzyme measurements in blood serum the physiological enzyme patterns in intestinal lymph and in serum of the rat were determined. The activities of lactate dehydrogenase, malate dehydrogenase, creatine kinase, myokinase and alkaline phosphatase were significantly higher in lymph than in serum, whereas sorbitol dehydrogenase, glutamate dehydrogenase, alanine aminotransferase and leucine aminopeptidase showed significantly higher activities in serum. The activity-ratios lymph/plasma varied between 0.26 and 2.78 compared to a value of 0.56 for total proteins. As for exogenous macromolecular substances there is a close correlationship between the molecular weight of the enzymes and their lymph/plasma-ratios. It can be shownthat under physiological conditions cellular enzymes enter the vascular system mainly by lymphatic transport and not so much by penetration across the capillary membrane. In addition patterns of enzyme activities were determined in mucosa and muscularis of duodenum and ileum as well as in intestinal lymph nodes. No direct correlation between the intracellular patterns and those in lymph could be found. It is assumed that the enzymes found in intestinal lymph nevertheless originate from those tissues but from aged cells which could have enzyme patterns different from the total cell population of the respective organ. Institut f~r Klinische Biochemie, Medizinische Hochschule, D 3000 Hannover 61, Karl-Wiechert-Allee 9 86 VITALMICROSCOPIC EXTRAVASCULAR G. Hauck and H.

RESULTS FLUID AND SchrSer

CONCERNING SUBSTANCE

THE EXISTENCE PATHWAY

OF

AN

The mechanisms regulating the extravascular transport of fluid and substances from the small blood vessels to the initial lymphatics essentially are still open. Numerous investigations suggest the existence of pump mechanisms or pressure gradients through the extravascular space. This does not agree however with the high flow resistance of the ground substance deduced from their physico-chemieal properties. Own investigations by means of the tracer respectively luminescence technique suggest the presence of an extravascular fluid and substance pathway - expecially for rnacromolecules as proteins -which exists preferably along the connective tissue fibres of the exlravascular space. The use of albumins marked by fluorescein-isothiocyanate shows a dye movement along the tissue fibres in dependence on the hemodynarnical conditions and the intraplasmatic pool of fluorescent protein. The reason can be seen in the existence of submicro-comnparfments between connective tissue fibres and ground substance which are characterized by a low flow resistance. Within these structures pressure gradients from the capillaries to the initial lymphatics can be effective. Furthermore, this exiravascular transport way would be marked by a transport capacity important for the maintenance of the fluid equilibrium in the tissue spaces. Department of Physiology, University of Miinster, D-44 Miinster/W., (Germany) Robert-Koch-Stra/~e 28

FI44 87 THE DIFFERENT ACTION OF CO,~ O N INSPIRATORY A N D EXPIRATORY BULBAR RESPIRATORY NEURONS. I<. Kolbe, "~M. Bilan, D. KIUl3endorfand H.P. Koepchen + The neuronal background of the ventilatory response to CO 2 was analysed from breath to breath in anaesthetized cats with the aid of computer analyses of bulbar insplratory (I) and expiratory (E) single neuron and phrenlc nerve (P) activity in relation to ventilatory parameters before and after exclusion of the vagl. 1 .) In I neurons and ~ discharge rate during bursts (RB) was closely related to the i-n-creasei-n ~ vdume under hypercapnia. Individual I neurons may deviate more or less in the extent and sometimes even in the direction of their response from the more predlctabk behavlour of P or multiple I activity. The number of impulses per burst (NB) increased less regulary than RB, but the mean value likewise increasedunder CO o because the augmentation of RB exceeded the slight mean decrease in burst duration (TB~ accompanlng the small decrease in insplratory time (Ti). No systematic deviation from this behaviour was observed after vagotomy 2.) In E neuro'ns a more inconsistent increase in RB occurred under CO but NB~ varied b e t w e e ~ c r e a s e and small decrease because the shortening of Tc " more or less balanced the ncrease n RB~. On the contrary after exclusion of the vagl NBr hkew,se increased under CO O to tile same degree as RB~ due to the nearly unchanged T~: ~nd therewith TBE. '~ T~e results confirm tfiat the respiratory neuronal response to CO,~ belongs to the type A responses (Koepchen 1974) and show that it is different in I and'E neurons9 The normal shortening of T~ under COo'occurs in spite of a higher E discharge rate. Thus in contrast to pulmonary re'flexes the a~tlon on respiratory frequency cannot be mediated by the E population, but presumably by an I mechanism. 9

.

.

i..

Department of Physiology, Frele Universit~it Berlin, 1 Berlin 33, Arnimallee 22 +Supported I:7 Deutsche ~':orsc.~lunasgemeinschaftand Stiftung Volkswagenwerk 88 THE ACTION OF HALOTHANE ON CENTRAL RESPIRATORY INNERVATION. M. Bilan, K. Kolbe, D. KIUl3endorf and H.P9 Koepchen+ The central mechanism of the depression of ventilation under halothane (Ha) was studied by means of extracellular mlcrorecordings from typical bulbar insplratory (I) and exsplratory (E) neurons and records of phrenlc nerve (P) activity in anaesthetized cats. Parameters of ventilatlon (pneumotachogram) and neuronal respiratory activity were contlnously computed and plotted. Inhalation of low concentrations of Ha (0,3-0,4%) resulted in immediate decrease in tidal volume closely parallel with decrease in arterial blood pressure, variable slight decrease in respiratory frequency with slight mean increase in insplratory time (Ti) , exspiratory time (Tr) and the T./T~ quotient. Discharge rate during bursts (RB) was dlmi'nshed more dlstinctly~than the number of ,mpulses per burst (NB) ,n I and P achvlty. The reaction of E neuronal activity to Ha was much more variable with prevailing decrease of RB and NB but to a minor degree than in I innervatlon. Sometimes also increase in neuronal E parameters or blphasic reactions were observed. In any case the quotient between neuronal I and E activity decreases under Ha, indicating a relatively higher depression of 1 activity. The general pattern of the reaction to Ha was not dependent on the integrity of the vagl. The results support the conclusion based on other types of noxious influences, that central I activity is more sensitive to injuries than E activity 9 The ambiguous response of E neurons is interpreted as an interaction between a direct inactivation by Ha and a dlsinhlbltion by the stronger inhibition of the reciprocal I population. Department of Physiology, Frele Universit'cit Berlin, 1 Berlin 33, Arnimallee 22 I

I::

.

.

.

.

.

+ Supported by Deutsche Forschungsgemeinschaft and Stlftung Volkswagenwerk

R 45 89 METABOLIC NETWORK

CONTROL OF NEURONAL PACEMAKER ACTIVITY IN THE RETICULAR RESPIRATORY G. BShmer, D. Dinse, M. Fallert and R.A.Chaplain

Biochemical regulatory mechanisms underlying the rhythmic changes in membrane potential have been elucidated in isolated pacemaker neurons. The allosteric metabolites governing the oscillatory enzyme activity are readily permeable across the neuronal membrane. This property of pacemaker neurons has been utilized to manipulate inspiratory and exspiratory pacemakers in the respiratory network. Using extracellular recordings with platinum electrodes (25/um diameter), the neurons have been identified according to their phase relation within the respiratory cycle and their response to artificial hyperventilation. Depending on whether a neuron became activated or inhibited following lung distension it was further classified as R~ or l~-type. When the respiratory neuron used for eleetrical~recording was perfused with a metabolite-containing liquor solution, there was a marked effect both on neuronal impulse pattern and the respiratory movements. With neurons which were truly active throughout the inspiratory phase activating modifiers of the intraneuronal regulatory system such as fructose diphosphate (F-],6-P2) , AMP, ADP or pyruvate in concentrations of 2-5 mM increased the spike density while the inhibitory modifiers ATP (bmM), citrate (]o mM) or 3-phosphoglycerate (8 mM) reduced the spike activity. In presence of theactivating modifiers the tidal volume and/or the respiration rate increased and the time intervals occupied by the inspiratory and exspiratory phases were shortened. The effects on the respiratory movements were essentially reversed in presence of the inhibitory metabolites. Opposite effects were noted when exspiratory neurons were perfused with the same metabolites, to the extent that F-I,6-P_ and AMP became now inhibitory while citrate actual~ increased the burst length~ Department of Physiology, University of Mainz, 65 Mainz, Obere Zahlbacher Str. 90 R E S P I R A T O R Y E F F E C T S OF I N T E R M I T T E N T E L E C T R I C A L IN THE R A B B I T M. F a l l e r t and K. Baum

BULBAR

STIMULATION

In a n e s t h e t i z e d r a b b i t s s p i r o g r a m and d i a p h r a g m a t i c a c t i v i t y were e x a m i n e d d u r i n g e l e c t r i c a l s t i m u l a t i o n of regions of the bulbar lateral r e t i c u l a r formation. The a c t i v i t y of b u l b a r r e s p i r a t o r y neurons was r e c o r d e d . One v o l l e y of r e p e t i t i v e stimuli per b r e a t h was applied. The v o l l e y was t r i g g e r e d by the animal's own r e s p i r a t i o n . One v o l l e y of some 150 msec d u r a t i o n at lO0 pulses per sec, applied d u r i n g i n s p i r a t i o n , caused an i m m e d i a t e and t r a n s i e n t i n h i b i t i o n of the d i a p h r a g m a t i c activity. A f t e r the end of the volley, the ins p i r a t i o n c o n t i n u e d . An i n s p i r a t o r y r e b o u nd appeared: the tidal volume was i n c r e a s e d above normal and the i n s p i r a t i o n was p r o l o n g e d . " I n s p l r a t o r y " n e u r o n s e x h i b i t e d i n h i b i t i o n during the volley; the b u r s t was l e n g t h e n e d and the spike d e n s i t y i n c r e a s e d after the vo~-Icy. The same was true for " e x p l r a t o r y - l n s p i r a t o r y " p h a s e - s p a n n i n g units. The d i s c h a r g e of " i n s p l r a t o r y - e x p i r a t o r y " p h a s e - s p a n n l n g n e u r o n s , however, was r a t h e r inhibited. When a p p l i e d during expir a t i o n the v o l l e y c a u s e d an i n s p i r a t o r y twitch, c o r r e l a t e d to a short p o s t - s t i m u l u s firing of " i n s p i r a t o r y " neurons. The burst of some p h a s e - s p a n n i n g units was shortened. The s t e r e o t a x i e m a p p i n g of the r e s p i r a t o r y n e u r o n s did not reveal a d i s t i n c t g r o u p i n g of i n s p i r a t o r y or p h a s e - s p a n n i n g units. R e s u l t s suggest that the bulbar s t i m u l a t i o n d i r e c t l y a f f e c t e d the f u n c t i o n of the r h y t h m - g e n e r a t i n g b u l b a r n e u r o n a l network. Dept. Obere

of P h y s i o l o g y , U n i v e r s i t y of Mainz, Z a h l b a c h e r S t r a s s e 67, G e r m a n y

D-65 Mainz,

R 46 91 E F F E C T OF P E R C E N T U A L W A T E R C O N T E N T D I F F U S I O N C O E F F I C I E N T OF D I S S O L V E D

IN T I S S U E S GASES

AND LIQUIDS P. V a u p e l

ON T H E

I n v e s t i g a t i o n s on d i f f u s i o n c o e f f i c i e n t D (r of d i s s o l v e d gases have s h o w n that D is i n v e r s e l y p r o p o r t i o n a l to the r a d i u s of the d i f f u s i n g m o l e c u l e and h e n c e to the root of the m o l e c u l a r weight. A set of e x p e r i m e n t a l d a t a for d i f f u s i o n of m o l e c u l e s w i t h d i f f e r e n t m o l e c u l a r w e i g h t s (MW < 1 , 0 0 0 ) in s e v e r a l tissues, h o w ever, d i d n ' t s u p p o r t this r e g u l a r i t y (SWAB~ et al., C a n c e r Res.34, 2814, 1974). T h e r e f o r e , the v a l i d i t y of this r e g u l a r i t y m u s t b e - r e s t r i g t e d to d i f f u s i o n c o e f f i c i e n t s of gases w i t h d i f f e r e n t m o l e c u l a r w e i g h t s or d i a m e t e r s i n one s p e c i a l tissue or one s p e c i a l s o l v e n t only. T h i s b e h a v i o u r m a y be a t t r i b u t e d t o v a r y i n g p e r c e n t u a l w a t e r c o n t e n t in t i s s u e s or liquids. U s i n g a v a i l a b l e l i t e r a t u r e d a t a for the d i f f u s i o n c o e f f i c i e n t s of (n=18), N2 (n=19), 02 ( n = 3 1 ) , and 0 0 9 (n=21) in several tissues, ~ becomes obvious that-with decreasing-percentual water content in t i s s u e s or l i q u i d s D is d r o p p i n g e x p o n e n t i a l l y , At p e r c e n t u a l w a t e r c o n t e n t s of a b o u t 85%, D is about one- h a l f the w a t e r value. D d e c r e a s e s to about 25% of the w a t e r value, the w a t e r c o n t e n t b e i n g 68%. C o m p a r i n g D for 0 o in d i f f e r e n t d i f f u s i o n m e d i a (tissues, KOH-, sucrose-, and h e m o g l o b i n s o l u t i o n s ) , no s i g n i f i c a n t d i f f e r e n c e s can be found, c o n s i d e r i n g i d e n t i c a l p e r c e n t u a l w a t e r contents. T h e r e f o r e , it can be s t a t e d that D is d e p e n d e n t not only on the radius of the d i f f u s i n g m o l e c u l e or on m o l e c u l a r weight, but also on the p e r c e n t u a l w a t e r c o n t e n t of the d i f f u s i o n m e d i a . Institute

of P h y s i o l o g y ,

University

of Mainz,

D 65 Mainz,

Saars~r.

g2 A SIMPLE AND PRECISE METHOD FOR THE CONTINUOUS DETERMINATION OF OXYGEN IN GASES AND FLUIDS IN THE RANGE OF nMOLES PER MINUTE H. U. Wolf, R. Zander, W. Lang On the basis of the well-known reaction of oxygen with alkaline pyrogallol an automated continuous photometric method has been developed For the precise determination of oxygen in gases and fluids with high reproducibility and sensitivity. The apparatus consists of a proportioning pump, a photometer with a 10 mm flow cell and a recorder. The tubing system of the pump pro~,ides a continuous flow of a standard alkaline pyrogallol solution together with a sensitivity increasing Fe2+ solution both permanently gased by purified nitrogen. After mixing the pyrogallol and the Fe2+ solutions as well as the oxygen containing gas or fluid behind the pump, the colour is allowed to develop within a few minutes at room temperature by passing mixing coils. The flow of the gas or fluid to be analyzed may be varied between 0.2 and 3 ml/min. Under these conditions amounts of oxygen can be deterhfined within a range of 10 to 500 nmoles per minute. Taking a flow of gas of about 3 ml/min an oxygen concentration down to a Value of about 20 ppm can be measured with an acceptable accuracy.

lnstffute of Biochemistry and Institute of Physiology, University of Mainz, D 65 Mainz, Saarstro~ 21

R 47 93 OXYGEN STORES IN HUMAN NERVOUS TISSUE R. Zander

After the circulation is arrested the tissue can maintain its oxygen consumption only for about some seconds due to the small size of oxygen stores, namely the chemical bound oxygen (Hb oF blood) as well as the physically dissolved oxygen (within blood, extravascular and intracellular space). For the computation ot: a so-called "oxygen store time"~ i.e. the time of Tschemia during which the tissue can get its energy aerobically, as a ratio between total oxygen store (ml 02/100 g) and oxygen consumption (ml 02/'100 g rain) the knowledge of oxygen solubility values is necessary. Measurement of oxygen solubility by the classical manometric VAN SLYKE method in human cerebral tissue at 37~ (diluted homogenatesw extrapolation to the undiluted starer calculation for intracellular conditions) led to the following data (ml 02/ml atm): white matter = 0.028, gray matter = 0.025 and whole brain of the newborn = 0.017. Estimation of oxygen solubility for the peripheral nerve tissue according to its chemical composition results in a value of 0.017 for the axon and 0.039 ml/ml atrn for the myelin sheath. High lipid concentrations, especially phospholipids obviously increase oxygen solubility in adult" nervous tissue over the value of aqua dest. (0.0241 ml/ml arm). Taking a mean oxygen partial pressure of 30 mmHg into consideration as well as literature data about oxygen consumption, the so-called "oxygen store time" reaches from 3 seconds (gray matter) to 14 seconds (white matter) while the physically dissolved oxygen amounts to 20 % of the total oxygen store (gray matter) or 45 % of the total (white matter). Institute of Physiology, University of Mainz~ D 65 Mainz~ Saarstral]e 21 94

VENTILATORY DRIVE OF COMBINED HYPOXIA AND HYPERCAPNIA IN RABBITS WITH ELIMINATED VAGI P. Kiwull, H. Kiwull-SchSne, W. Balster and E. Balster-De Beer Earlier experiments indicated that the v e n t i l a t o r y d r i v e mediated by a constant peripheral chemoreceptor input(electrical stimulation of one cut sinus nerve) became less effective, if an additional hypercapnic drive was induced. This loss of efficiency, however, was partly masked b y the influence of vagal afferents. In consequence, the combined ventilatory effect of a constant hyp oxic stimulus and hypercapnia was tested with intact peripheral chemoreflexes, with intact vagi (PflGg.Arch. 355, R36,1975) and now with both vagi cut: in anaesthetized rabbits the PaC02 was increased stepwise during hyperoxia as well as during constant hypoxia. Blood gas and acid-base values, ventilation, blood pressure and heart rate were measured.Hypoxia alone caused a distinct hyperpnea(~6~% of control)and concomitant hypocapnia. Additionally PaC02 led to a further strong ~ncrease of ventilation. With the sam~ increase of PaCOp the average increase of ventilation over the. .whole .. rancho of t~,~ C02 -resp~ curve was significantly_ lower under hypoxla than under hyperoxla, more pronounced towards the upper part. As compared with the results of the population with intact vagi, the same hypoxic drive was less effective under comparable hypercapnic conditions.Since these findings are in agreement with the results from electrical activation of chemoreceptor afferents under hyperoxia, a C02-dependent effect of vagal afferents on the efficiency of the peripheral chemoreflex drive of ventilation may be assumed.(Supported by DFG/SFB 115) Inst.f.Physiologie,Ruhr-Universit~t

Bochmm, D-4630 Bochum

R 48 95

INFLUENCE OF HYPOXIA ON TIDAL VOLUME AND RESPIRATORY CYCLE TIME COMPONENTS WITH AND WITHOUT VAGAL AND/OR CAROTID CHEMORECEPTOR AFFERENTS H. Kiwull-SchSne and P. Kiwull In anesthetized rabbits,tidal volume and time components of breaths were investigated under hyperoxia, normoxia~ and two levels of hypoxia(FIOo:1.00, 0.21, 0.12, 0.07). At steady states, data were taken with intact and cold-blocked vagi, as well as with intact and cut sinus nerves. - With intact sinus nerves, n= 10, an~ intact(or cold-blocked) vagi, u~der hyperoxia, the ~ean value - S.E. of tidal volume VT§ 8.520.6(11.310.6)ml.kg-',and of total cycle duration TT 2.0 -0.2(2.6-0.2) s. The portion of inspiratory duration TI was 32(@4)%, of exspiratory duration TE 36(35)%, and of interval after exspiration TL 32(21)%. With decreasing P~O,, Vm increased hyperbolically to m~x. 9.910.6(16.0 0.9)ml-kg- ~ h e r ~ a s TT decreased to 1.3-0.I(2.110.2) s, mainly due to a reduction of TL(TI). T With cut ~inus nerves~ n=5~ under hyperoxia, V T was 8.0lO.9(~0.1Z1.1)ml.kg-',TT 1.9Z0.3(2.310.3) s. Neither V T nor cycle time components were significantly different from those measured with intact sinus nerves. With decreasing P a ~ V m decreased hyperbolically to max. 6.550.9(8.3• and TT decreased (increased) to ~ . 6 X 0 . I ( 2 . ~ 0 . 5 ) s, mainly d~e to a reduction(augmentation) of TL. For each experimental condition~ a linear,highly positive correlation between V~ and TT was found. The ratios V~/TI, V~/TE, V~/TL, in sum representing ~, were in different ways ~epende~t on P~Oo~ influenced by vagal and carotid chemoreceptor afferents. Their ~elative roles for the resulting ventilation will be discussed. Inst. fGr Physiolo~ie, Ruhr-Universit~t,

@6~ Boch~m Postfach 2~48

96 RESPONSE OF NEURONS IN THE VENTRAL MEDULLARY SURFACE TO ALTERATIONS OF H § I0N CONCENTRATION IN THE CEHEBROSPINAL FLUID. M.E.Schlaefke, W.R.See, and A.Herker The firing rate of different neurons within the chemosensitive areas on the ventral medullary surface can be influenced by intravenous injec -

tions of HCI or NaHC07 (Schlaefke et al., Bull.Physiopathol.resp. 11, 277-284,1975). In the~e experiments however the behaviour of CSF pH may have been equivocal. For this reason the frequency of action potentials of neurons within the ventral medullary surface (intermediate area) in anaesthetized cats was recorded during local superfusion of bicarbonate buffers of pH 7.0 or pH 7.6. pH on the ventral medullary surface was measured continuously with a glass electrode. A unit, firing with 2.4 imp./sec under control conditions, increased its mean firing rate over 160 sec during superfusion with a buffer of pH 7.0 to 4.7 imp./sec. The

maximum frequency was 20.5 imp./sec 50 sec after the start of superfusion. At this moment a second neuron appeared, firing with 49.7 imp./sec in the average. The frequency of this neuron fell gradually to 15 imp./ sec, and the neuron was silent 60 sec after the superfusion had been stopped. The first neuron continued firing during superfusion withthe buffer of pH 7.6. Its mean frequency over 180 sec was reduced to 2.5 imp./sec, the lowest frequency being 2.1 imp./sec. This suggests that a change of pH in the CSF does not only influence the discharge frequency of neurons within the ventral medullary surface but may also have a recruiting effect in the chemosensitive areas. Supported by DFG (SFB 114 'Bionach') Institut fGr Physiologie, Lehrstuhl I, Ruhr-Universit~t Bochum, D-4630 Bochum

R 49 97 INFLUENCE 0 F M U S C U L A R EXERCISE ON RESPIRATION AFTER CENTRAL AND PERI PHERAT, CH~0DENERVATION. R.Spode and M.E.Schlaefke As shown by Schlaefke et al. (1969), and by See (197~), non chemical respiratory d r i v e s a r e not able to maintain ventilation if central chemosensitivity and peripheral chemoreceptors are eliminated. In hyperthermia or during electrical stimulation of the anterior hypothalamus respiration can be maintained in the absence of chemical drives (See, 1975). The question arose, whether or not the respiratory drive during muscular exercise needs the chemosensitive drives. In cats, anaesthetized with ketamine hydrochloride and chloralose/urethane, the caudal art of the sectioned ventral roots of L7 was electrically stimulated unipclar, 0.5-2 V, 20-100 Hz, I msec). Stimulation caused movements of one or both hindlimbs. The central chemosensitive mechanism was reversibly eliminated by bilateral cold block of the intermediate area (area S) on the ventral medullary surface (Schlaefke and Loeschcke, 1967). Sinus nerves and v a g i w e r e cut. Before cold block stimulation of the ventral roots caused an increase of ventilation from 741 ml/min to 1458 ml/min, and of respiratory frequency from 15/min to 26/min. During cold block stimulation continued to produce movements of the hindlimbs, but the influence on respiration was lost. These observations indicate that under the conditionsof our experiments the influence of muscular exercise on respiration is dependent on the mechanism which is blocked by the elimination of the intermediate area.

~

Institut fur Physiologie, Lehrstuhl I, Ruhr-Universit~t Bochum, 9-4630 Bochum. 98 MDRPHOLOGICAL DESCRIPTION CF MEDULLARY RESPIRATORY NEURONS OF THE CAT. (Morphologische Beschreibung von medull~ren ,respiratorischen Neuronen der Katze). F.Kreuter, R.Senekowitsch and D.W.Richter In chloralose anaesthetized, paralyzed and vagotc~ized cats medullary respiratory neurons were recorded intracellulary with micropipettes (0,5-I /urn, 40-100 M~) filled ~ith a saturated solution of Procion Yellow MX-4R. The neurons were identified by antidrcntic excitat/on after intraspinal and vagal nerve stimulation and were dyed by application of 2-10 nA hyperpolarizing dc-currents for 240 min. For dye diffusion within the cells the cats were kept alive for 2-10 h after marking. After 10% formalin fixation 10 /um thick transverse sections were cut frcm parablast-embedded tissue. Exam/b~tions were made with a Leitz fluorescence microscope using BG-12 and K 510 filters for the exciting and emi~ tted light respectively. Totally 84 neurons were attempted to stain but only 40% of the cells were recovered within the sections. All those neurons were located within the retroambigual region. Stained vagal neurons (VRN) were observed to lie close by cells of the same shape (minimal distances MD I00-300 finn), but only smaller cells generally were found near by (MD 50-80 /urn) stained bulbospinal neurons (SRN). Inspiratory and expiratory neurons of the individual groups of cells showed a similar morphology. The scmata of SRNs were spindleshape, with 8-22 ./~m~and 23-67 /urnin diameters. Most of the VRNs and antidromlcally not-defin@d neurons (NI~) were globular-shaped. Former cells were 22-45 ~, latter cells 12-28 /tun in diameter. Scme spindle-shaped VRNs revealed diaers of 6-22 /um and 45-80 ~um. The number of-dendrites arising from the soma was 4-6 in SRNs, 5-8 in VRNs ~nd 4-6 in NRNs. Dendrites could be traced for a distance of up to 400 /tun. The distant dendritic branches faded out at a diameter of I /tml.Axons we~ce identified in 2 VRNs. They were traced for a distance of 200 /urn. No collaterals were seen leaving the parent axon. Physiologisches Institut der Universit~t, 69 Heidelberg I, Neuenheimer Feld 326

R 50 99 C O R R E L A T I O N OF V E N T I L A T O R Y P A R A M E T E R S AND PATTERNS OF PRRENIC M O T O N E U R O N D I S C H A R G E IN TRE R E S T I N G AND P A N T I N G C A T K. P l e s c h k a , W. Riedel and C.L. ~ebber, Jr. The discharge patterns of single phrenic m o t o n e u r o n s (fiber splitting technique) were c o m p a r e d with v e n t i l a t o r y parameters in urethane a n e s t h e t i z e d and s p o n t a n e o u s l y b r e a t h i n g cats at rest and during panting. P a n t i n g was p r o v o k e d by heating the p r e o p t i c / a n t e r i o r h y p o t h a l a m i c region Or increasing the deep body temperature. During thermal polypnea, there was a significant d e c r e a s e in the number of impulses per burst and in t~e durati o n of the discharge phase so that a reciprocal relationship existed b e t w e e n these parameters and the r e s p i r a t o r y rate. The mean impulse and instantaneous peak frequencies were higher w i t h i n the burst during panting than eupnea and the peak frequencies were reached earlier in the train. Likewise, the thermal drive increased the rate of change of air flow (volume acceleration) and d e c r e a s e d the tidal volume. These results suggest that the v e l o c i t y of airflow is in part dependent upon the rate of frequency rise in phrenic m o t on e u r o n s while the volume of each b r e a t h is r e g u l a t e d by the duration of the inspiratory phase. S i g n i f i c a n t contributions from the external intercostal muscles are also implied. M a x - P l a n c k - l n s t i t u t f~r P h y s i o l o g i s c h e und K l i n i s c h e Forschung, W.G. K e r c k h o f f - l n s t i t u t , D'6350 Bad Nauheim, Germany.

100 CORRELATION BETWEEN THE MAXIMAL AEROBIC POWER AND THE OXYGEN AFFINITY IN MAN. E. Humpeler, E. Knapp, E. Raas, P. Deetjen Recent investigations of the influence of exercise and physical activity "n the oxygen affinity of hemoglobin have revealed rather contradictory results. Therefore this study was undertaken to provide information as to whether a correlation exists between maximal aerobic power and the oxygen affinity of hemoglobin. With a Radiometer oxygen dissociation curve analyzer the oxygen affinity, which is defined by the Pbo value (half saturation tension of oxygen) of 33 young non-smoking males was determined. Furthermore the following parameters were measured with a J~ger Ergo-Pneumo-Test:

the maximal aerobic

power (definedas the highest oxygen uptake the individual could attain during physical work) expressed in liter oxygen/min and milliliter oxygen/min/kg/B.W. and the oxygen pulse and oxygen pulse per kg B.W. A significant postive correlation was found between P5o-values and maximal oxygen uptake during physical9

indicating the higher the maximal aerobic power the lower the

oxygen affinity of hemoglobin. Institute of Physiology, University of Innsbruck, SehSpfstra~e 41, A - 6020

Innsbruck, Austria

R 51

101 A COMPARATIVE STUDY OF OXYGEN TRANSPORT IN BIRD BLOOD P. Baumann, R. Baumann~ R. Bartels and H. Bartels The oxygen affinity and Bohr effect have been measured in the blood of several species of birds to clarify the controversial findings of Lutz et al. (Resp. Physiol. 17:265-275, 1973, and 20:325-330, 1974) who reported much higher values for bird blood oxygen affinity than other authors and also found a satisfying correlation between body weight and oxygen affinity. In addition they observed a decrease of the oxygen affinity when decreasing the PCO 2 . Under physiological conditions (41~ pH 7.5, PCO~ 39 mm Hg) the Pr O of hen blood was 52.5 mm Hg. A reduction of P~O~ from 40 to O~mm Hg resulted in a decrease of the Pr O by S.7 mmZHg. This effect of CO~ on oxygen affinity is qualitatively comparable to that observed for mammalian blood. Additional experiments in hemoglobin solutions support the results obtained for whole blood. The P~O of quail and pigeon blood was 42.9 and 36.0 respectively. A correlation between body weight and oxygen affinity could not be established from our nor all other published data. We propose that the oxygen affinity of bird blood is aside from dependence on metabolic rate influenced by the habits of the birds such as high altitude flight and diving. Physiologisches Institut, Medizinische Hochschule, Karl-Wiechert-Allee 9

D 3 Hannover,

I02 THE ALVEOLAR-ARTERIAL 02-DIFFERENCE OF OXYGEN PRESSURE IN RELATION TO A L V E O L A R GAS TENSIONS

J.P. PICHOTKA,

J. ENGELHARDT,

G. CAROLI, K.D. SCHUSTER

AaDO 2 was determined as difference of end-exspiratory 02-tension measured b y mass-spectrometry and 02-tension of the capillary blood from the hyperemic ear-lobe determined b y the Eschweilerelectrode.

1300 determinations were performed on more t h a n 4 0

persons breathing 02-N2-mixtures with 17 to 30% 02. The results show that the observed AaDO 2 is characteristically related to alveolar 02-and C02-tension. Department of Physiology,

University of Bonn, Nussallee dl D 53 Bonn

R 52 103

TH~ METABOLIC ACTIVITY OF DIFFERENT PARTS OF THE DIAPHRAGM THEMOUSE H.M. SOM~[ER~ H.J. SCHMIDT

OF

The metabolic activity of the whole diaphragm decreases with a characteristic function o f age and b o d y weight. This observation could be explained on the assumption that the different tissues have a different metabolic activity and that their mass relation changes w i t h age. The different parts of the diaphragm were therefore investigated seperately. Pars costalis and pars lumbalis can easily be separated. The weight relation of these two parts is approximately 2 and independent of age and size. The metabolic activity is highly different; m e a n values for the pars cestalis are close to 38 ml Oo/kg. min and for the pars lumbalis close to 20 ml Oo/kg. min. T~e metabolic activity of these two parts decreases i~ identical manner with age and body-weight of the animals. In the same experiments was observed that b y division of the pars costalis into several pieces rate and stability of oxygen uptake were definitely influenced. Department allee ~I

of Physiology,

University

of Bonn,

D 53 Bonn, N u s s -

104

OXYGEN TENSION AND OXYGEN UPTAKE IN THE ISOLATED DIAPHRAGM OF THE MOUSE H.J. Schmidt, M. Sommer, H. Weigand and J.P.Pichotka With the classical Warburg technique high shaking rates (120 cycles per minute or more) are used to ensure equilibrium of oxygen tension between gaseous and liquid phase. The oxygen uptake observed under these conditions is considered to be determined by oxygen tension. In work of our laboratory it was shown that high shaking rates per se strongly influence rate and stability of oxygen uptake. According to our experience shaking rates of more than 50 cycles per minute should not be used in work with isolated tissues of high metabolic intensity. In experiments on the isolated diaphragm of the mouse at 40 cycles per minute oxygen tension of the liquid phase and O~uptake were measured simultaneously. With 21 to 60 % OgoinZthe gaseous phase (corresponding to 150 - 430 Torr O~ at 37 C sat.) the 02-tension in the liquid phase was between 100 and well above 300 Torr. Oxygen uptake in these experiments was directly proportional to the O2-tension in the liquid phase and remained stable for hours. Changes of oxygen tension within this range were immediately answered by proportional changes in O2-uptake. Department allee 11.

of Physiology,

University

of Bonn, D 53 Bonn, Nuss-

R53

105 EFFECTIVENESS

OF HUMAN TEMPERATURE

- REGULATION

J. Wex~ner

The stationary and dynamical behaviour of the control-system of human temperature-regulation were determined by way of systems i ~ l a t i o n on a digital computer as well as by way of climatic chamber experiments. The experimental results confirmed on the whole the mathematical concept, which had te be adjusted only in certain details. In order to evaluate the effectiveness of control we compared the results achieved with intact regulation with those obtained under open loop conditions. The results reveal interesting regiopal differences Of effectiveness of control. A considerable effectiveness is reached regarding the central areas of head and t r n ~ , especially after cold-loading, whereas the extremities profit only to a very moderate extent from the activities of the control-system. After cold-loading, as far as hands and feet are concerned, the'results achieved under open loop conditions are even better than under closed loop conditions. This confirms very distinctly the fact, that peripheral temperatures, although co,~mnnicated by afferent fibers to the controlcenters, are not virtually controlled by the effector-mechanisms. Institut fur Physiologie, Lehrstuhl II, Ruhr-Universit~t, D ~63 Bochum, ~Universit~tsstr. 150, Geb~ude MA 4 I06 THE ROLE OF SHORT-TIME ADAPTATION 0F MAN K.: Behling, A. Bleichert,

IN THERMOREGUI~TORY and M. Scarperi

BEHAVIOR

During steady state, thermoregulatory behavior may be predicted by s i m p l e a l g e b r a i c equations, using skin- and deep-body temperature (Ts, Tes) as input variables (Bleichert et al., PflGg. Arch. 338,~303 (1973), Scarperi et al., PflGg. Arch. in press). In all experiments, the subjects resting or exercising totally immersed in a water bath, could adjust either the most comfortable temperature of the water (Tcomf) or the preferred temperature of a restricted area of their backs (Tpref). During transients, Tcomf and Tpref (at constant Ts) as a function of Tes deviate in a characteristic manner from values obtained during steady state. During the phase of falling Tes, Tcomf is lower and Tpref is higher than during the phase of rising Tes at the same Tes. The findings are explained in terms of adaptation of thermal sensation evoked by receptors in the skin and in the core. In a mathematical model which predicts thermoregulatory behavior as a function of thermal stimuli, adaptation of thermal sensation is t a k e n into account. Adaptation is introduced into the model as an exponential decrease of sensation in response to a rectangular change of Ts or Tes. This model fairly predicts transient responses in thermoregulatory behavior. Physiologisches Martinistr. 52

Institut,

Universit~t

Hamburg,

D 2 Hamburg 20,

R 54 107

CALCULATIONS OF THE CORE TEMPERATURE CHANGES IN MAN AS A FUNCTION OF METABOLISM, THERMAL ENVIRONMENT AND TIME E, Hundhausen, B. Theves and E. Witzleb The formulas which were derived for the symmetry of constant average curvature by B. Theves (see the preceding paper) are applied to some practical cases. The calculations that do not rely on the unrealistic assumption of thermal steady state show the experimentally known time phase shift between metabolism and core (rectal) temperature. Measurements of the circadian temperature rhythm are compared with calculations where metabolism, clothing and/or climatic conditions are varied. It can be shown that very small variations of these parameters can be responsible for the observed temperature changes. The combined effect of climatic variations and strongly increased metabolism is demonstrated by comparing computed values with experiments of Givoni and Goldman (J.Appl.Physiol. 32(6), 812-822, 1972). Institut f~r angewandte Physiologie und medizinische Klimatologie der Christian-Albrechts-Universit~t, 2300 Kiel, 01shausenstr. 40-60. 108 THE SOLUTION OF THE TIME DEPENDENT HEAT TRANSFER EQUATION FOR THE HUMAN BODY BY THE SYMMETRY OF CONSTANT AVERAGE CURVATURE B. Theves, E. Hundhausen und E, Witzleb The general importance of the average surface curvature for heat conduction problems is explained and a special symmetry with constant average curvature on the isothermal surfaces is defined. The applicability for the body shapes of homeothermic organisms is demonstrated. The heat transfer equations are solved for sudden changes of climatic environment and/or metabolism. The numerical calculations were made with the help of a digital computer program. The results, values for the temperatures as a function of body area and time, are presented in form of diagrams. Institut f~r angewandte Physiologie und medizinische Klimatologie der Christian-Albrechts-Universit~t, 2300 Kiel, Olshausenstr. 40-60.

R 55 109

THERMOGENETIC RESPONSES ON ELECTRICAL STIMULATION IN THE DORSOLATERAL PART OF THE PONTINE TEGMENTUM IN THE GUINEA-PIG. Z. Szel@nyi, E. Zeisberger and K. Brdck Bipolar stainless steel stimulating electrodes were chronically implanted into pontine areas, which were presumed to be parts o5 the ascending noradrenergic system. In addition, guide cannulas for injection of noradrenaline (NA) were introduced into the anterior hypothalamus at the same side. The experiments were carried out on 10 unanaesthetized guinea-pigs, aged 9 to 24 days, at an ambient temperature of 30~. Points in the pons were found, the stimulation of which resulted in a rise of oxygen uptake (up to 40 to 80% over the resting level), of deep body temperature and of local temperature in the interscapular adipose tissue. Respiratory frequency doubled, on average, during stimulation; electrical activity, measured in two muscle groups, showed only a slight increase. These responses were compared, in the same animal, with reactions obtained after an intrahypothalamic NA injection (2~g) and were found to be very similar. When the electrical stimulation of the pons was repeated several times, the extent of rise in oxygen uptake became gradually smaller, amounting to only half of the initial response after four periods of stimulation. An intrahypothalamic injection of NA restored the effectiveness of pontine stimulation to the initial extent. These results suggest that the thermogenesis evoked by the electrical stimulation of the pons may be ascribed to the activation of noradrenergic pathways terminating in the hypothalamus. Zentrum f~r Physiologie der Universit~t, D 63 Giessen, Aulweg 129 110

NONSHIVERING THERMOGENESIS INDUCED IN THE RAT BY REPETITIVE COOLING OF THE HYPOTHALAMUS, AND OF THE SPINAL CORD. M. Banet and H. Hensel To study how the development of nonshivering thermogenesis seen during cold exposure is controlled, thermodes were implanteC into the preoptic area of six white male rats, and into the spinal canal of another 10 animals. Both thermoreceptive areas were then continously cooled, nine hours per day five days a week, to a level that induced a sustained increase in oxygen consumption of 60 - 70%. After 50 to 150 hours of cooling, oxygen consumption was measured at 30 C before and one hour after a subcutaneous injection of noradrenaline (0.4 mg/kg). Following the noradrenaline injection, the preoptic-cooled animals increased oxygen uptake by 81%, and the spinal cord-cooled ones by 71%, while their corresponding controls, also fitted with thermodes, increased oxygen uptake by only 37 and 33%, respectively ( p ~ O . 0 1 ) . Despite this increased capacity for nonshivering thermogenesis, the experimental animals did not tolerate exposure to cold better than the control ones, showing that other factors also play a significant role in cold adaptation in the rat. This development of nonshivering thermogenesis could explain the shift from shivering to nonshivering thermogenesis seen during adaptation to cold. Institute of Physiology, University of Marburg, D-3550 Marburg, DeutschhausstraBe 2 Supported by the Deutsche Forschungsgemeinschaft.

R 56 111

Changes of Glycolytic E n z y m e Activi%ies and Mitoehondrial Respiration in Mice after Temperature Acclimation and Chronic Poisoning A. M a l a s e k +) & A. Locker 4-+) Male HalCR mice were adapted for 6 weeks to 3 different ambient temperatures (12.5; 22.5 and 32.5oc). After termination of adaptation, the activities of the glycolytic enzymes hexokinase (HK) pyruvate kinase (PK) and lactate dehydrogenase (LDH) were assess ed in liver, skeletal muscle, heart, brain and kidney and in liver also mitochondrial respiration has been measured. In other experiments mice have been pretreated during the last 14 days of temperature adaptation with daily administered 6 mg/kg arsene oxide (As203). As against room temperature HK is mostly ~owered after cold- and warm adaptation, PK varies considerably and LDH is increased after cold. The enzyme activities are profoundly altered by arsene oxide. Mitochondrial respiration (states 3 and 4) is increased both after cold and heat adaptation. As compared with the increase brought about at room temperature by As203 the enhancement after combined influence of temperature acclimation and arsene oxide is less pronounced thus exhibiting a protective action of temperature adaptation to warm and cold against poisoning. +) Biophysics Unit, Ir~titute of Biology, Austrian Research Centre Seibersdorf-Vienna, A 1082 Vienna ++) Department of Biophysics, University of Technology, A 1040 Vienna 112

Effect of Temperature Acclimation, Irradiation and Solcoseryl Treatment on the Activity of Glycolytic E n z y m e s and Tissue Respiration in Mice F.E. Keller+), D. Bauer+)& A. Locker ++) The radioprotective effect of heat acclimation could be improved by solcoseryl. To approach the action mechanism, male HaICR mice exposed to 32.5oc for 6 weeks have been irradiated with 900 rad -rays and during the following 3 days the enzymes glucose-6hosphate dehydrogenase (G-6-PDH) and lactate dehydrogenase (LDH) etermined in liver, kidney, testes and thymus. The effect of solcoseryl, daily 12 mg/30 g for 3 days, on the activities of these enzymes after heat acclimation and additional irradiation has been explored. Tissue respiration (Gilson apparatus) of liver has been measured also after acclimation to 12.5o. With exception of liver LDH enzyme activities are lowered after irradiation. Solcoseryl increases liver and kidney LDH and kidney and thymus G-6-PDH in non-irradiated animals, this effect being less pronounced after irradiation. Liver respiration after heat exposure is lower than after cold; solcoseryl treatment corroborates this difference which is also maintained after temperature adaptation and irradiation. The results explain the ability of solcoseryl to act curatively after irradiation only in dose dependence.

~

+) Biophysics Unit, Institute of Biology, Austrian Research Centre Seibersdorf-Vienna, A 1082 Vienna ++) Department of Biophysics, University of Technology, A 1040 Vienna

R 57 113

ROLE OF ROSTRAL BRAIN STEM T H E R M O S E N S I T I V I T Y IN TEMPERATURE R E G U L A T I O N OF THE ADELIE PENGUIN. E, Simon, H.T. Hammel, Ch. Simon~Opp:~rmann,i E. Karl, J . Maggert. in 4 Adelie penguins the temperature of the rostral brain stem , was c o n t r o l l e d by chronically implanted thermodes. Thermal stimulation was p e r f o r m e d in the conscious u n r e s t r a i n e d animals at c o n t r o l l e d ambient temperatures. Oxygen consumption and temperatures in the esophagus, in the rostral brain stem and at the skin of one w i n g were c o n t i n u o u s l y recorded. Rostral brain stem heating in a thermoneutral environment (+9~ increased skin blood flow. In the Cold (-20~ when the animals shivered and the skin vessels were constricted, rostral brain stem heating reduced oxygen uptake but did not release v a s o c o n s t r i c t i o n in the skin with the stimulus intensities applied. Esophageal temperature fell m o d e r a t e l y during heating. Weak cooling of the rostra1 b r a i n stem in a~thermoneutral environment had insignificant v a s o c o n s t r i c t o r effects in the skin but stronger coollng induced vasodilatation. In the cold~ oxygen uptake was reduced by rostra1 b r a i n stem cooling. Esophageal t e m p e r a t u r e fell during cooling but its decrease was moderate indicating strong f e e d back signals from elsewhere in the body. It is concluded: The Adelle penguin's rostra1 brain stem contains I ) t e m p e r a t u r e sensors c o n t r l b u t i n ~ signals only in the range of normal to elevated core t e m p e r a t u r e s and 2) integrative and/or efferent neurons of the t e m p e r a t u r e regulation system the activities of w h i c h decrease with their own temperatures. M a x - P l a n c k - l n s t i t u t fur P h y s l o l o g i s c h e und Klinlsche Forschung, W.G. K e r c k h o f f - l n s t i t u t , D - 6 3 5 0 Bad Nauheim, Germany. t14 ROLE OF SPINAL CORD THERMOSENSITIVITY IN TEMPERATURE REGULATION

OF THE ADELIE PENGUIN. Ch. Simon-Oppermafin, K.T. Hammel, E. Simon, R. Kaul, J. Maggert. In 6 AdeliH penguins the temperature of the lower cervical and upper thoracic spinal cord was controlled by chronically implanted thermodes. Spinal thermal stimulation was p e r f o r m e d in the conscious u n r e s t r a i n e d animals at controlled ambient temperatures. Oxygen consumption and temperatures in the esophagusj at the skin of one wing and of the spinal canal thermode were continuously recorded. In a thermoneutral environment (+9~ spinal cord heating increased and cooling decreased skin blood flow~ whereas oxygen consumption changed insignificantly. In a cold 9 O 9 ~ environment (-20 C), when oxygen consumption was slightly elevated due to shivering and the skin vessels in the wing were perm a n e n t l y constricted, spinal cord heating decreased and coollng increased oxygen consumption, whereas skin blood flow was not influenced with the stimulus intensities applied. The slopes of the r e g r e s s i o n lines relating the changes of heat production to O spinal canal temperature were -0.05 W/kg/ C in the thermoneutral environment and -0.52 W/kgL~ in the cold. During spinal thermal s t i m u l a t i o n esophageal temperature changed in a direction opposite to that of the spinal canal. These core temperature changes were m o d e r a t e indicating strong negative feedback signals from elsewhere in the body. The effects of spinal thermal stimulation on core t e m p e r a t u r e suggest that spinal t h e r m o s e n s i t i v i t y decreases with decreasing spinal cord temperature. M a x - P l a n c k - l n s t i t u t fur P h y s i o l o g i s c h e und K l i n i s c h e Forschung, W.G. K e r c k h o f f - l n s t i t u t , D-6350 Bad Nauheim, Germany.

R 58 115 INFLUENCE OF S P I N A L I Z A T I O N ON T E H P E R A T U R E RESPONSES OF A S C E N D I N G SPINAL N E U R O N S IN CATS. Eva B e r g h e i m ~ K a e k m a n n a n d E. S i m o n O b s e r v a t i o n s in s p i n a l i z e d cats (Simon, E., Pfl~gers Arch. 337, 323-332, 1972) have revealed a high degree of c o n v e r g e n c e b e t w e e n spinal and cutaneous t e m p e r a t u r e signals in ascending spinal neurons. - C o m p a r a t i v e i n v e s t i g a t i o n s were carried out in s p i n a l i z e d and intact animals. Single unit activity was recorded from w a r m and cold sensitive a s c e n d i n g units of the a n t e r o l a t e r a l spinal tracts at C~ - C.. In case of s p i n a l i z a t i o n the spinal cord was t r a n s e c t e d ~t th~ level of CI/C 2. The temperatures of the thoracolumbar spinal cord and of the skin of the trunk and hind legs were i n d e p e n d e n t l y varied. - N e i t h e r in cold nor in w a r m sensitive units were there any d e t e c t a b l e differences in the s e n s i t i v i t y to changes of the spinal cord temperature b e t w e e n s p i n a l i z e d and intact animals. However, substantial differences were o b s e r v e d with respect to the skin temperature effects: In s p i n a l i z e d animals n e a r l y all cold sensitive spinal units were systematically i n f l u e n c e d by cutaneous t e m p e r a t u r e stimulation, but in intact animals this effect was rather the exception than the rule. On the other hand, the effects of skin t em p e r a t u r e on a s c e n d i n g spinal w a r m sensitive neurons w e r e n o n - s y s t e m a t i c both in intact and spinal animals. M a x - P l a n c k - l n s t i t u t f~r P h y s i o l o g i s c h e und K l i n i s c h e Forschung, W.G. K e r c k h o f f - l n s t i t u t ~ D-6350 Bad Nauheim~ Germany.

116 EFFECT OF H Y P O T H A L A M I C H E A T I N G ON LINGUAL BLOOD FLOW AND R E S P I R A T I O N IN THE A N E S T H E T ! Z E D D O G . H. K r S n e r t and K. P l e s c h k a It has been suggested that increased lingual blood flow and thermal p o l y p n e a under heat load may be induced by a common central i n t e g r a t i n g m e c h a n i s m (W. K i n d e r m a n n and K. Plesehka, Pfl~gets Arch.340, 251-262, 1973). We i n v e s t i g a t e d lingual blood flow and r e s p i r a t o r y rate as influenced by p r e o p t i c / a n t e r i o r hypothalamic heating (water p e r f u s e d thermode) in urethane a n e s t h e t i z e d dogs at constant body temperature. Lingual blood flow was measured e l e e t r o m a g n e t i c a l l y and was found to be 20 mi/min at a respiratory rate of 60 c y c l e s / m i n at rest. During h y p e t h a l a m i c heating, r e s p i r a t o r y rate increased m a r k e d l y depending upon the p e r f u s i n g temperature, a n e s t h e t i c level and p o s i t i o n of the thermode. At an average frequency of I00 cycles/min, lingual blood flow increased in a stepwise m a n n e r and was p o s i t i v e l y correlated with the respiratory rate. This flow increase resulted from a decrease in the local v a s c u l a r resistance since the driving systemic p r e s s u r e remained constant. At m a x i m u m r e s p i r a t o r y rates lingual blood flow reached a level of about 60 ml/min. When p e r f u s i o n of the thermode was stopped, both r e s p i r a t o r y rate and lingual blood flow r e t u r n e d to control values w i t h i n 5 minutes. Similar changes in lingual blood flow did not occur in dogs in w h i c h a v e n t i l a t o ry response failed to be elicited during h y p o t h a l a m i c heating. These results c o n f i r m the concept that panting, a s s o c i a t e d with increased lingual blood flow, are induced by a common autonomic outflow p a t t e r n w h i c h is m e d i a t e d by the central m e c h a n i s m controlling thermal homeostasis. MPI

f~r P h y s i o l o g i s c h e

und K l i n i s c h e

Forschung,

D-635

Bad N a u h e i m

R 59 117 EFFECTS OF AIR TEMPERATURE ON SPINAL AND H Y P O T H A L A M I C SENSITIVITY IN A COIq~CIOUS G O A T Claus ~s,san

THERMO-

A goat with chronically implanted thermodes was subjected to various combinations of h y p o t h a l a m i c (T~,,)and spinal (T ) temperatures at different levels of air temperature (To). M ~ a b o l i s m (M) and respiratory evaporative heat loss (REHL) were measured. At T +]O~ and +30~ M rose nonlinearly with decreasing T_ below ~l~ At T a +30~ M reached its maximum at T h 34~ f~ther cooling having no additional effect. At T +]O~ ~ rose steeper until m a x i m u m cooling intensity was applied. - At T +IO~ and +30~ spinal cooling increased M maximally at the ~ost intensive level of cooling. At low T.a , M rose with spinal cooling at a steeper slope, - The comblned effects of hypothalamic and spinal cooling on M could be described by an addition of the single temperature stimuli, while skin (following T ) and core (T, and Tsc) temperature stimuli interacted n o n a d d i t i v ~ l y in drivingnYM. In these experiments, REHL followed almost exclusively T_ . At T +30~ REHL rose with T_ above 39~ Since M reached ~ s minim o n . mum at Th, 41 C (see above~, heat p r o d u c t l o n and heat loss responses overlap, thus providing sensitive dual adjustment of heat balance at normal body core temperature. This is reflected by the fact that the change in core temperature, which was induced by the effector responses, had its steepest slope around normal body temperature. M a x - P l a n c k - l n s t i t u t fHr P h y s i o l o g i s c h e und Klinische Forschung, W.G. K e r c k h o f f - l n s t i t u t , Bad Nauheim, und Zentrum fHr Physiologie der Universit~t, Giessen, Germany 118 E L E C T R O M Y O G R A P H I C A L SHIVERING IN THE RABBIT INFLUENCED BY PERIPHERAL AND CENTRAL THERMAL STIMULATION. W. Riedel Investigations in rabbits on thermoregulatory effector systems controlling heat loss and recordings of splanchnic afferents have revealed a predominant w a r m sensitivity within the abdominal cavity. To determine the mode of interaction between abdominal w a r m sensors and peripheral and central cold sensors in the control of heat production, e l e c t r o m y o g r a p h i c a l shivering (EMA) was recorded @nd q u a n t i t a t i v e l y evaluated, Skin temperature was controlled by a water p e r f u s e d coat, thermal stimulation of the dorsal abdominal wall and the spinal cord was performed by means of water p e r f u s e d thermodes. - Cooling the skin increased EMA starting at a mean skin temperature of 34 - 35~ EMA increased linearily with falling skin temperature. At external temperatures of 15~ 20 and 25~ abdominal or spinal heating decreased EMA inducing a shift of the regressio n llne without a change in slope. At conditions of combined extern&l and spinal cooling, abdominal heating reduced EMA. This reduction was greater at higher shivering intensities, causing changes in the slope of the regression line. Thus, in the control of shivering spinal and abdominal t h e r m o s e n s i t i v i t y interact with cutaneous cold sensitivity by changing the thresholds. In contrast, abdominal warming and spinal cooling appear to interact by mutually influencing the sensitivity of the h e a t p r o d u c t i o n control system to each of both central temperature signal inputs. M a x - P l a n c k - l n s t i t u t fHr P h y s i o l o g l s c h e und Kllnische Forschung, K e r c k h o f f - l n s t i t u t , D-6350 Bad Nauheim, Germany.

W.G.

R 60 119

CHARACTERISTICS OF THERMOSENSITIVE PREOPTIC NEURONES IN A HIBERNATOR. W. ~dnnenber~ ' and G. Merker The observation that hibernators increase their core temperatures by about 30~ during arousal leads to the question of the existence of preoptic neurones capable of sensing hypothalamic tempm~at~res (Thy) during arousal, i.e. in a temperature range far below those of ~uthermy. To answer thisTquestion , thermosensitivity of preoptic units was studied at hy ranging from 10~ to 43~ in golden hamsters in a non-hibernating state as well as in guinea pigs. In golden hamsters 2 typesTof preoptic neurones have been found that seem suitable to sense hy during arousal: 1) Units with a bellshaped temperature-firing rate characteristic, a negative temperature coefficient at Thv 40~ to 30~, a maximal activity at Thy 20~ to 25~ and a high temperature sensitivity (+2 to +4 Imp/ sec 9 ~) even at Thv close to I0~. 2) Neurones sensitive at Thv ranging from 10~ to-40~ with an exponential characteristic and ~ very high spontaneous firing rates (50-70 Imp/sec) at Thv 36~ to 37~. These types of units could never be recorded in our-studies pigs. In this species, thermosensitive units of the P0/ became inactive or insensitive to thermal stimulation as soon as Thy f e l l b e l o w 30~. Our studies are a well-fitting ne~rophysiologiSal supplement to previously reported experiments in hibernating ground squirrels, in which arousal induced by a drop of the ambient temperature could be reversed by warming the P0/AH (Heller, H.C. and H.T. Hammel: Comp. Biochem. Physiol. 41A, 349359, 1972). Zentrum fur Physiologie,

D 63 Giessen, Aulweg 129.

120

THE INFLUENCE OF M E T E S ON INTESTINAL ABSORPTION OF SOME MODEL SUBSTANCES. E.Beubler and F.Lembeck Previous findings have shown that theophylline (2 mg/ml) and caffeine (2 mg/ml) injected into the intestinal lumen increase intestinal blood flow by 85% and 66% respectively.The influence of this drug-induced increase in blood flow on the absorption of model substances was investigated.Jejunal loops of anaesthetized rats were filled with the model substances in buffered isotonic solutions.Blood flow and appearance rate (=absorption rate) were determined by_ collecting the venous outflow of the jejunal vein in 5 min.intervals.Blood pressure was kept constant at 60-80 ~ Hg by adjustable supply of blood from donor rats (~inne D. ,N.S.Arch.Pharmacol.,254,199,1966).The model substances were:HTO and 14C-urea at pH 7 (hydr.ophilic,unionized),14C-antipyrine at pH 8 (lipophilic,not dissociated) and 14C-salicylic acid at pH 6 (almost completely dissociated) .It was found that the methylxanthine-induced increase in intestinal blood flow caused a significant enhancement in absorption rate of all model substances. The increase in absorption was most pronounced with antipyrine (+50%) followed by HID and urea (+35%).Absorption of salieylic acid was less affected (+23%).The results show thatdrug-induced increase in blood flow causes a more pronounced e n h a n c ~ t in absorption of drugs than increasing blDod flow by elevating the blood pressure,a method used by W.Ochsenfahrt & D.Winne (N.S.Arch. Pharmacol. ,264,55,1969).Under otherwise con~arable conditions they found an increase in absorption rate by only 0-20%.This discrepancy corresponds to the findings of J.Svanvik (Acta physiol.scand.suppl.,385,1973) who proved that mucosal blood flow (and therefore absorption) is more increased by vasodilators than by altering perfusion pressure. Department of Pharmacology,University of Graz,A-8010 Graz ,Universit~tsplatz 4

R 61 121 EFFECT OF CARBOHYDRATE-FREE ISOCALORIC DIET ON INTESTINAL ABSORPTION OF CARBOHYDRATES (IN-VITRO-EXPERIMENTS IN RATS) J.M. Eisenhardt, H.-G. St~ckert, R. Dennhardt and F.J. Haberich How does intestinal absorptive capacity of male and female rats vary in relation to active and passive transport of carbohydrates(CH) glucose (G), 3-O-methylrD-glucose (MG), sorbose (S) and 3-O-methylD-glucose + 5.10-4 M Phlorrhizin (MG+P) at carbohydrate-free (less than 1%-portion), isocaloric (5,5 kcal/g) diet(CH-F-D) comnared with controls on normal diet (CH-portion 66 %, 5,3 kcal/g)? I week, 2,4,6,8,10,12 and 15 weeks after beginning the feeding, experiments are carried out in the proximal jejunum by the method of J.SEMENZA (BBA 173, 104 (1959). In regard to G and MG, female CH-F-D-rats, from t-~ second week after beginning of the feeding on to the 15th week, show a significantly higher uptake in the intestinal mucosal cell. The rate of transport of S in CH-F-D-rats lies significantly below controls. The CH-F-D-rats and the controls show no difference in regard to the intracellular uptake o f MG+P. Contrary t o female rats, in male rats there is no difference in the intestinal absorption in regard to all tested substrates, when feeding a CH-F-D. Conclusion: I)B 7 feeding rats a CH-F-D, elevated intestinal absorption takes place only in the case of actively transported substrates. 2)Cause for this could either be an increase in the number o f carriers, or an increase in the affinity between hexose-carriers and their substrates, when CH is absent from the diet. 5)The diminished absorption of S in the case of feeding a CH-F-D hints at some specific influence of this diet on the structure of the intestinal cell membrane. 4)On17 female rats are concerned by the mentioned functional changes. Institute of Applied Physiology, University of Marburg, D 555 Marburg/L., Lahnberge 122 EFFECTS OF FASTING ON GLUCOSE METABOLISM AND GLUCONEOGENESIS IN RUMINANTS J.Leibetseder

In a more complex research project about gluconeogenesis the influence of fasting was also st~@ied in three lactating cows using Glucose-6-T and Alanine-U- ~C. Blood plasma concentration, pool-size, space, and flux of glucose and alanine were determined after 12 and 84 hours of fasting before and during i.v. glucose load with 2.2 mg/kg B.W. x min. The contribution of alanine tc gluconeogenesis under different c o n d i t i o n s w a s calculated also. A combined simple shot, and constant infusiontechnique was c a r r i e d o u t . The,results showed a siginificant reduction of glucose flux as well as a significantly diminuished glucogeneogenesis from alanine after 84 hours of fasting.

Institut fur Physiologie, Tier~rztliche Hochschule, Linke Bahngasse ii, A-1030 WIEN This study was carried out at the university of California, Davis, supported by a grant from U.S. Institute of Health, Grant, No. HD-02375

R62 123

EXPERIMENTS

F O R ESTIMATION

OF THE BIOLOGICAL

AGE OF THE RAT

Kment,A.,G.Hofecker,H.Niederm~ller The experimental

study of factors

is of great medical rats,

interest.

influencing

the a g e i n g p r o c e s s

For this type of experiments

a test p r o g r a m was developed

to estimate

age using a series of standard age parameters: turation-tension 2.solubility

and solubility

of collagen

3.stress-strain

parameters

ters of the aorta, organs, vity,

8.parameters

calculated

of learning

a statistical

from the parameters of Physiology,

Linke Bahngasse

4.stress-strain activity

and memory. measure

dena-

of the tail tendon,

content of heart and brain,

ferent age and experimental Institute

of the skin,

l.isometric

content of the corium,

5.succinicdehydrogenase

6.1ipofuscine

riate analysis,

of collagen

and hexosamine

with

the biological

parame-

in various

7.motor acti-

By means of multiva-

for the biological

age is

and can be used to compare

dif-

groups of rats.

Vet.med.University,

A-lo3o Vienna,

ii

124

CHANGES

IN SOME AGE PARAMETERS

PHYSICAL TRAINING

(treadmill)

and restricted

the influence

diet

of physical

(2 fast-days

a week)

activity, 2.running performance,3.soluble

tendon,

skin,

of the aorta,6.conc,

and trace elements

of plasma

were divided

and 8.of succinic

stricted diet,no

training,3.diet

m o t o r activity(photographically were sacrificed tute.

Preliminary

and 7.of

960 rats

training,2.re-

ad libitum,training,4.restricted of the running endurance and electronically)the

and the parameters

standard methods

in tail

dehydrogenase, 9.

l.diet ad libitum,no

After assessment

rats:

of the tail-

of lipofuscine

lipids and lo.of plasma cholesterol.

into 4 groups:

diet,training.

on the fol-

collagen

aorta and lung,4.denaturation-tension

tendon,5.elasticity conc.

training

was explored using male Sprague-Dawley

l.motor

minerals

DIET AN~

Niederm~ller,H.,A.Kment,G.Hofecker

In a three year-test program, lowing parameters

OF THE RAT BY RESTRICTED

and the

animals

were determined partly by

and p a r t l y by methods

developed

in our insti-

results of 8-1o cnd of 15-17 months old rats

are presented. Inst.Physiol.,Vet.med.Univ.,A-lo3o

Vienna,Linke

Bahngasse

ii

R 63 125

REGULATION OF METABOLISM BY EXTRACELLULAR RIBONUCLEASE AND NUCLEOSIDASE IN MOULDS J. Meyrath and A. Leschnik Self-inhibition and self-stimulation effects in moulds have been shown to be governed by,densities of population and/or inoculum (J. Meyrath, Antonie van Leeuwenhoek 29, 57, 1965; J. Meyrath & A.F. McIntosh, Canad. J. Microbiol. I~, 1965). Two specific extracellular proteins have been held responsible for this regulatory effect in Aspergillus ~ (J. Meyrath & E. Roth, Experientia 29, 1168, 1975). The purification of these proteins has now been perfectionated and the two compounds turned out to be ribonuclease and a nucleosidase respectively. They, individually or in combination,inhibit germination of conidia, mycelial growth and respiration. Not all ribonucleases (of different origin) cause this effect, only ribonuclease A seems to be effective. The most likely interpretation of this inhibition by extracellular and surfacebound nucleases is that of interference with nutrient transport similar to the effect of ribonuclease in Neurospora crassa (W.D. Stuart & D.O. Woodward, J. Bact. 122, 41, 1975),where ~-h-~nzyme t inhibited uptake of phenylalanine b-y--the cells.

Institute of Applied Microbiology, University of Agriculture,Peter Jordan-Strafe 82, 1190 Vienna. 126

m-RNA, ISOLATED FROM CONIDIA OF ASPERGILLUS ORYZAE, AND ITS GROWTH-STIMULATING PROPERTIES A. Leschnik and J. Meyrath Conidia of A. oryzae were treated by sodium loride, sodium dodecylsulfate and EDTA. The resulting extract was precipitated by ethanol (70 % v/v) and fractionated on Biogel A 1.5 m. The eluate containing one of the peaks (26o nm) showed very strong properties in respect of germination and of mycelial growth. The activity of the compund(s) was not lost by treatment with phenolsodiumdodecylsulfate nor with desoxyribonuclease. However, treatment with ribonuclease A rendered the fraction inactive. Considering that fraction could be resolved into another biologically active fraction by separation on polyuridylated Sepharose, the conclusion seems to be warranted that the sought-for compound is a m-RNA. This compound might be responsible for self-stimulating effects observed in moulds and governed by population d~S~ty. Institute of Applied Microbiology, University of Agriculture, Peter Jordan-StraSe 82, 119o Vienna.

R64 127

F O R C E ~ V E L O C I T Y - R E L A T I O N OF D E P O L A R I Z E D SMOOTH MUSCLE D E S C R I B E D BY A MODEL OF I N T E R A C T I O N B E T W E E N VISCOUS FLOW AND C O N T R A C T I O N W . R o e c k e m a n n and J . M u e l l e r - O n t j e s experi m e n t s on taenia eoli of guinea pig show that stretch and s h o r t e n i n g under v a r i a t i o n of load after d e p o l a r i s a t i o n by potassium are not symmetric. At d i f f e r e n t loads near the e q u i l i b r i u m (v=0, K=Ko) the constant v e l o c i t y of s h o r t e n i n g or stretch was measured. The f o r c e - v e l o c i t y - c u r v e changes its slope similar to Hill's equation by a factor 8 when c h a n g i ng the load between K o • 0.7.Ko We assume that the e q u i l i b r i u m results from a superp ositi o n of the v e l o c i t y of s h o r t e n i n g (active) and the v e l o c i t y of stretch (viscous) and this yields also beyond the equilibrium. Since changes of length correspond to changes of energy we define c o n t r a c t i l i t y by power (L). And we tested the assumption, that power is ~ constant at d e p o l a r i z e d muscle. The h y d r a u l i c analogon: a dashpot (viscosity~), w h o s e leaking current is c o u n t e r a c t e d by a pump with the c h a r a c t e r i s t i c s i-p = L = const., leading to the equation: v = K ~ - L/K ~ a n d L are n o r m a l i z e d to area and length of muscle, e l a s t i c i t i e s are n e g l e c t e d here). It follows: Ko =~--~ ; dv/dKIv=o = 2/~ This means that at e q u i l i b r i u m the a p p a r e n t v i s c o s i t y of the whole s y s t e m is just half of the dashpot's viscosity. By s u b t r a c t i n g the viscous flow ( c a l c u l a t e d as above) from the m e a s u r e d total v i s c o s i t y one gets the v e l o c i t y of c o n t r a c t i o n (pump) as a function of load: the result can be d e s c r i b e d by a h y p e r b o l a w i t h o u t additive constants, in a c c o r d a n c e with our assumption L=const. = v-K. Zentrum der P h y s i o l o g i c , A b t e i l u n g K r e i s l a u f D6 F r a n k f u r t / M a i n , Theodor-Stern-Kai 7

,

128 STRESS R E L A X A T I O N A F T E R S T R E T C H AND F O L L O W I N G A C T I V E R E A C T I O N S IN V E R T E B R A T E S M O O T H M U S C L E B.Hohorst, U . K r 6 h n e r t and K . G r e v e n The time course of r e l a x a t i o n after sudden s t r e t c h (2,5 mm fo E ~ --T 10 to 15 m m initial length) was i n v e s t i g a t e d w i t h rela X ed (Ca d e p l e t i o n + D 600) in c o m p a r i s o n with c o n t r a c t e d (KC1 and KoSO ~ d e p o l a r i z e d ) taeniae coli~ The samples were s t a n d a r d i z e d with ~ r e s p e c t to the r e c i p r o c a l value of their volumes to make such a c o m p a r i s o n possible. The e x p e r i m e n t s were p e r f o r m e d in p a r a l l e l to e a r l i e r ones w i t h creep. Stress r e l a x a t i o n occurs by far quicker and obtains a g r e a t e r extent in c o n t r a c t e d than in relaxed muscles. Also, these r e a c t i o n s are more p r o n o u n c e d with K~S0. than w i t h KC1 d e p o l a r i z a t i o n . This can be u n d e r s t o o d by the s w ~ l l ~ n g caused by KCI in excess (Jones et al., J . P h y s i o l . 2 3 2 , 247 (1973)). The r e l a t i o n s b e t w e e n the extent of r e l a x a t i o n d u r i n g its time course (R) and its v e l o c i t y (dR/dr) are h y p e r b o l i c (Greven et al., PflGgers Arch.344, 245 (1973)), w h i c h can be e x p l a i n e d by inner f r i c t i o n b e i n g a linear f u n c t i o n of R, or by the a s s u m p t i o n that t r a n s v e r s a l bonds were b r o k e n d u r i n g stress relaxation. Both interp r e t a t i o n s can be covered by the same equations. Slow active c o n t r a c t u r e s , sometimes of m a x i m a l extent and l a s t i n g t h r o u g h hours were seen f o l l o w i n g stress r e l a x a t i o n in the contracted d e p o l a r i z e d muscles. H o w e v e r no r e l a t i o n could be d e t e c t e d b e t w e e n the p a r a m e t e r s of r e l a x a t i o n and those of the f o l l o w i n g active reaction. Zentrum

der Physiologie,

D 6 Frankfurt

(M), Theodor

Stern Kai 7

R65 129 CREEP AFTER LOADING OF SMOOTH MUSCLES UNDER D I F F E R E N T CONDITIONS K.Greven, K.H.Rudolph and B.Hohorst

OSMOTIC

The tae~iae coli of guinea pigs were submitted to elastic extension ( ~ ) and creep (N) by loading in the relaxed (Ca'T,depletlon +verapa~il) as well as in the contracted (K~SO 4 - depolarized) state in isotonic (314 mosm), hypotonic (207 mosm) and hypertonic (463 mosm) bath solutions. If standardized with respect to their volumes in isotonic solutions before the beginning of the experiments, there was no difference in the total length (initial length before loading + 1 E + N) at the end of the experiment (2000 sec = ca. 33 min) for the relaxed state under the different osmotic conditions. Identical results were seen with contracted preparations if compared among one another, though all contracted preparations showed a greater total length than the relaxed ones irrespective of their osmotic conditions. All muscles whether relaxed or contracted did obey the laws of creep stated in an earlier paper (Greven et al.,Pfl~gers Arch.344,245 (1973) in all solutions used. The results suggest that the elastic and especially the viscoelastic behaviour of smooth muscles is independent of the water content of the cells i.e. the viscosity of the plasma and probably bound to solid structures (s.Bozler,J. C e l l . C o m p . P h y s i o l . 1 8 , 3 8 5 (1941), Amer. J.Physiol.171~359 (1952)). Models with springs and dashpots which stand for vlscous resistance can only be of limited value to imitate the viscoelastic behaviour of smooth muscles. Zentrum der Physlologie,

D 6 Frankfurt

(M), Theodor Stern Kai 7

130 THE USE OF SPECTRAL ANALYSIS FOR THE EXAMINATION OF SPONTANEOUS CONTRACTIONS OF SMOOTH MUSCLES H.Hinghofer-Szalkay, Th.Kenner and W. Estelberger The aim of our study was to reexamine the use of spectral analysis of spontaneous contractions of smooth muscles for the description of the basic features of these events. We used segments of portal vain and uterus of rats and recorded isometrically and/or isotonlcally for 1 hour. In both organs the power spectrum showed several peaks which apparently correspond to harmonics of the fundamental frequency. Our results indicate that this type of spectrum can be explained simply by the appearance of harmonics due to the particular shape of the contractions. Furthermore, in the portal vein we observed a localized pacemaker region which induces a quite regular rhythm. Basar, who made similar experiments (PflHgers Arch.352,135,1974), found characteristic peaks of the power spectrum at frequencies appearing different from those corresponding to harmonics. He compared the spontaneous fluctuations of the flow in the perfused rat kidney with the spontaneous contractions of guinea pig taenia coli and vena~portae. We could not find a good agreement between Basars spectra of perfused rat kidneys and our spectra of rat smooth muscle preparations. Our results, furthermore, indicate that spectral analysis should only be used in connection with other methods. Supported by Osterreichlscher Fonds zur FSrderung der wissenschaftlichen Forschung Physiologisches Institut, Hniversit~t Graz, A-8OIO Graz Mozartgasse 14

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INFLUENCE OF C A L C I U M O N THE K I N E T I C S O F C R O S S - B R I D G E M O V E M E N T IN T HE V A S C U L A R SMOOTH M U S C L E U. Johnson~ M. E h l , R. L a v e n t U. P e i p e r The k i n e t i c s of c r o s s - b r i d g e m o v e m e n t was s t u d i e d by m e a n s of a f t e r l o a d e d i s o t o n i c c o n t r a c t i o n s of the t e t a n i z e d r a t p o r t a l v e i n . U n d e r c o n t r o l c o n d i t i o n s (pH 7 . 3 , p C a 2 . 6 ) the f o l l o w i n g p a r a m e t e r s of the f o r c e v e l o c i t y r e l a t i o n w e r e c a l c u l a t e d : a of H i l l ' s e q u a t i o n ( r e l a t i n g to the t o t a l tension) -- 0 . 3 6 ; b ( r e l a t ing to m u s c l e length) = 0 . 1 9 M L / s ; Vo ( r e l a t i n g to m u s c l e length) = 0 . 5 6 M L / s . C h a n g e s in e x t r a c e l l u l a r p C a ( 3 . 1 5 - 2.1) o r p H ( 8 . 0 - 6 . 8 ) as w e l l as n o r a d r e n a l i n e ( 0 . 4 ~ g / m l ) added at a pH of 5 . 9 a f f e c t e d the c h a r a c t e r i s t i c s of muscle contraction quite similarly: there was a pronounced variation in force generation whereas the extrapolated velocity of shortening at zero load (Vo) remained unchanged. It is supposed that these experimental conditions control the intracellular calcium concentration which influences the number of activated interaction sites rather than the velocity of cross-bridge movement. At a pH below 6.8, however, V decreased; this effect is probably caused by a direct influence on the ATP~ m a x i m u m activity and calcium sensitivity were diminished as demonstrated by the corresponding shift of the calcium dose-response curve. The small V o at low extracellular calcium (pCa 3.4) might suggest a lack Of activated contractile units under these conditions. Noradrenaline added at a pH of 5.9 potentiated the force generation probably by increasing the n u m b e r of activated interaction sites, whereas the sustained low speed of shortening indicat ed only a slight effect of noradrenaline on the velocity of cross-bridge movement. P h y s i o t o g t s c h e s I n s t i t u t , D - 87 W f i r z b u r g , R 6 n t g e n r i n g 9

132 RABBIT V E N A CAVA CONTRACTIONS NORADRENALINE

(NA)

AFTER REPEATED

SHORT PULSES OF

M. Vonderlage

With our technique (Vonderlage, Eur. J. Pharmacol.25, 71, 1974) which permits addition of very short pulses of NA, virtually excluding the development of the slow tonic response to NA, we investigated the fast component of the rabbit vena cava contraction using a normal physiological salt solution. Experimental conditions which are known to increase the cellular calcium content (e.g. transient incubation between s~imulations in a K~-free solutiqn,o~ ~ a solution with high [K ~ , in a solution with high LCa ~ % or in a solution containing ouabain (10- M) ) lead to a n increase in contraction amplitude. When the duration of a single stimulus in a train of NA stimuli is prolonged the next following Gontraction decreases. With increasing incubation time in Ca z+ -free s o l u t i o n t h e maximum of contraction amplitude decreases considerably more after repeated stimulation than after a single stimulus. The results suggest that the fast component of the rabbit vena cava contraction which is induced by NA is related to the cellular calcium content and that the pronounced decrease in contraction amplitude after repeated stimulations using a Ca 2+free solution may be due to a loss of cellular calcium favoured by the shortlasting addition of NA which causes a release of Ca 2+ from cellular storage sites. Physiologisches Institut Grindelallee 117

der Universit~t,

2 Hamburg

15,

R 67 133

02RECEPTORS IN THE INTRAMURAL NERVOUS SYSTEM OF THE GUINEA-PIG ILEUM AND COLON? C.J. Mayer and J. Riemer Discharge of spontaneously active enteric neurons has b e e n r e p o r ted. In the presence of xylocaine (Sx10-5gr/ml) or TTX (Ixi0 -7 gr/ml) the circular muscle layer of the guinea-pig ileum and colon shows an increase in tone and motility in vitro. These findings show the existence of a tonic inhibition of the gut. If the Krebs solution is bubbled with 95% N 2 and 5% C02 the circular muscle layer relaxes. After readmission of 02 this effect is completely reversible. However, if the Krebs solution is bubbled with N 2 in the presence of xylocaine or T T X n o

relaxation occurs.

On the other hand, if xylocaine or TTX is added during the N 2 induced relaxation s spontaneous contractions reappear. In the ileum, however, single twitch-like contractions occur during exposure to N2" These contractions can be blocked with atropine. The findings indicate that gut wall tone may be controlled by partial oxygen pressure within the intramural ganglia. Dept. of Physiology, Univ. of Munich, D8 Munich 2, Pettenkoferstr 134 M I C R O C I R C U L A T I O N A N D OXYGEN SUPPLY IN SKELETAL MUSCLE UNDER PHYSIOLOGICAL AND PATHOLOGICAL CONDITIONS. K. Sch6nleben (I), B.A. Krumme (2), B. B611ing (2), M. Kessler (2) Local oxygen tension was measured in the gastrocnemius muscle of rats and dogs with the multi-wire surface electrode during respiration with gas mixtures containing 40 %, 20,9 %, 15 % and 10 % oxygen. One group of rats was anesthetized with ether and one group with pentobarbital. In contrast to the rats anesthetized with ether, the rats anesthetized with Pentobarbital show disturbances of microcirculation. Respiration with 40 % oxygen causes a noticeable worsening of the local oxygen supply. The reason for this alteration might be a too drastic counter regulation. Even slight hypoxia causes marked pathological shifts, whereby the state of training of the animals evidently influences the sensitivity of the animals to hypoxia. In hemorrhagic shock, even minimal bleeding produces ~noxic fields in the tissue. The experiments show clearl~ that the measurement of local oxygen pressure in the skeletal muscle is a sensitive indicator for the regulation of the microcirculation. (I) Chirurgisehe Universit~tsklinik M~nster - Allgemeinchirurgie, D-44 Mfinster, Jungeblodtplatz I (2) Max-Planck-Institut ffir Systemphysiologie, D-46 Dortmund, Rheinlanddamm 201

R 68 135

THE TIME COURSE OF MECHANICAL ACTIVATION AND DESACTIVATION Db~ING THE ISOMETRIC TETANUS OF FROG'S SKELETAL MUSCLE E. Rumberger Guick stretch and q u i c k r e l e a s e experiments are used in order to study the interactions between mechanical activation and desactivation during the plateau phase of an isometricotetanus in a skeletal muscle (m. semitendinosus, frog, 0 to 15 C; length changes: I-2 % of resting muscle length within 30 msec). Results: I. During the plateau phase of the tetanus stiffness increases with time. 2. During the same time the rate in stress relaxation subsequent to a quick stretch increases, the rate in recovery subsequent to a quick release decreases. 3. The stiffness resulting from stretch experiments depends on temperature with a Gin -value -2. Conclusion: The plateau phase of a tetanic contraction may reflect a state of balance between two counteracting processes whose intensity decreases with the same rate. This is in agreement with the well known facts of decreasing heat-development during the plateau-phase of the tetanus and the decrease of relaxation velocity after stimulation with increasing duration of the plateau phase. Institute of Physiology, Martinistr. 92

University of Hamburg, D 2 Hamburg 20,

136

POTASSIUM AND CHL4?RIDE: A REASSESSMENT IN MAMMALIAN S K E L E T A L MUSCLE. H. R e n n e r and W. W e s t p h a l A c c o r d i n g to BOYLE and CONWAY ( J . P h y s i o l . 100, 1-63j 1941) c h l o r i d e i s p a s s i v e l y d i s t r i b u t e d in the s a r t o r i u s m u s c l e of the f r o g . R e c e n t s t u d i e s u s i n g a c h l o r i d e s e n s i t i v e m i c r o e l e c t r o d e have shown that t h i s does not hold t r u e f o r n o r m a l m e m b r a n e r e s t i n g p o t e n t i a l s (Kernan~ M a c D e r m o t t , Wesfl~ha~ J. P h y s i o l . 241~ 60P-61P~ 1974). T h e r e e x i s t s a c o n s i d e r a b l e d i f f e r e n c e b e t w e e n E m and EC1 i n d i c a t i n g an e x c e s s of i n t r a c e l l u l a r c h l o r i d e . The a i m of the p r e s e n t i n v e s t i g a t i o n on the d i a p h r a g m of the r a t has b e e n to e s t a b l i s h the r e l a t i o n s h i p b e t w e e n p o t a s s i u m and c h l o r i d e c o v e r i n g a wide r a n g e of o u t s i d e p o t a s s i u m c o n c e n t r a t i o n s ( d u r a t i o n of the e x p e r i m e n t s up to 2 h, 3 8 ~ 2 4 Ko~ 128 m m o l e s / 1 ) . - With i n c r e a s e d Ko the f i b r e s gained m o r e c h l o r i d e a n d l o s t l e s s p o t a s s i u m . The s u m o f s o d i u m and p o t a s s i u m r e m a i n e d v i r t u a l l y c o n s t a n t . O u a b a i n (10-4M) e n h a n c e d the d e c r e a s e of p o t a s s i u m r e m a r k a b l y but e x e r t e d a c o m p a r a t i v e l y s m a l l effect on c h l o r i d e uptake. A l o g - l o g r e l a tion b e t w e e n Ko- C1o a n d C1i (eStimated)/C1 i (expected f r o m p a s s i v e d i s t r i b u tion) fits m o s t of the data. The r e s u l t s s u g g e s t that t h e r e is an e x c e s s of c h l o r i d e w i t h i n the m u s c l e f i b r e the a m o u n t of which is a. ) i n v e r s e l y r e l a t e d to the e x t e r n a l p o t a s s i u m c o n c e n t r a t i o n , and b . ) s u b s t a n t i a l l y r e d u c e d by ouabain. Dept. of P h y s i o l o g y , U n i v e r s i t y , D 8700 Wfirzburgo R 6 n t g e n r i n g 9 +) Supported b y a g r a n t of the D e u t s c h e F o r s c h u n g s g e m e i n s c h a f t

R 69 137

FORCE GENERATION BY CROSS BRIDGE BENDING: N E W MECHANICAL AND STRUCTURAL EVIDENCE. H. J. Kuhn, G. Beinbrech, J. W. Herzig and J. C. RGegg Huxley and Simmons (1971) proposed a contraction model, according to which the myosin heads of the cross bridges attached to the actin filaments exert mechanical force by bending from a vertical to an acute angle, whereby stretching an elastic component of the cross bridge. This contraction model is now supported by new structural and mechanical studies with glycerol extracted fibres from Lethocerus. Bundles of 7 to iO fibres were (partly) relaxed in a physiological salt solution containing AMPPNP, a non hydrolyzable ATP analogue, in place of ATP. Cross bridges changed from a vertical to an angled position, as judged from electron mycroscopical studies, when washing out the analogue, whereby an isometric contraction occurred, whereas fibre stiffness, measured according to Huxley and Simmons, is not increased. This suggests that the tension was generated by bending of already attached bridges and not by attaching of previously unattached cross bridges. This is clearly shown by a parallel left shift of the tensionlength plot (T1 curve of Huxley and Simmons). II. Physiologisches Institut der Universit~t, D-69 Heidelberg, Im Neuenheimer Feld 326 Zoologisches Institut der Universit~t,D-44 MGnster 138

Sr2+-INDUOED TENSION IN ISOLATED BUNDLES OF FROG HYOFIBRILS: THE KINETICS OF RF~t0TION D.G. Hoisescu and R. Thieleczek Thin bundles of f r o g (iliofibularis, Rana esculenta) myofibrils (diameter c. 5 0 m) have b esn activated at 22oC in solutions containin@ EGTA-buffered [SrL+J, following a procedure previously described (Ashley & Zolses.cu, J. Physiol. 2 . ~ , 8P, 1973). All solutions cont.ained (raM):[K+J 100; LATP] 4; LTES[-6--uffer 10 (pH=7.10 + 0.02)~ freeCHgJO.1. In order to facilitate a rapid equilibration of Sr ~ in ~he cross-section of the pre~aratio~n ~ the , myofibrils have been actlvated in solutlons where LEGTA~ + LSr-EGT~ =20 mH after beSng kept for 3-5 min. in a 'low' relaxing solution ([EGTA] = 0.2 mH) (see Ashley, Campbell & Moisescu, J. Physiol. 2#~, 9P, 1975). The solutions also contained various C1- concentrations for the neutralization of the cations. Under these conditions, a steep sigmoid relationship is obtained between steads-state isometric tension and [Sr ~, implying a cooperative action of Sr ions in the process of tension development. 50% of the maximal tension iSaachievedtf~ th t the ra e o ension ~ d v 1.1 ,M. An important observation is 9 elopment is strongly dependent upon [Sr 2+] in the activating solutions, suggesting that the rate of tension development is limited by reaction steps in which Sr 2+ is directly involved. The simplest scheme of reaction consistent with both steady-state and transient experiments is a 'consecutive' one: ~ 2+ .. a 9 -- ~-2+ b 9 . ~r + zl ~ ~rz, + ~r ~ ~ r 2 M ~ Tension where + [Sr + ~ constant ( oisescu thesis, 1974) and c, d (s-l") 0.22, 0.046; a, b (H-1 s -d) 4.4 - dO 4, 2.3 - dO 5. Lehrs~uhl Zellphysiologie, Ruhr-Universit~t, 463 Bochum, Postfach

R 70 139

STUDIES MUSCLE

ON THE O R I G I N OF LATENCY R E L A X A T I O N M. H e r b s t and P. P i o n t e k

OF S K E L E T A L

A c c o r d i n g to a h y p o t h e s i s of H i l l ( J. Physiol. Lond. 199, 637, 1968 ) latency r e l a x a t i o n of skeletal muscle is caused by a d e t a c h m e n t of c r o s s - b r i d g e s b e t w e e n the m y o f i l a m e n t s w h i c h exist even in r e s t i n g m u s c l e and contribute to the r e s t i n g tension. Imposing r e p e a t e d l y small Changes in l e n g t h ( triangular waveform; amplitude: < 1 % of the slack length; velocity: 0 . O 1 % - 10 % of the slack l e n g t h p e r sec. ) on a frog's toe muscle p r e p a r a t i o n ( slack l e n g t h about 6~mm; initial sarcomere l e n g t h about 2,7 p m ), it is p o s s i b l e to d e t a c h these resting cross-bridges, as i n d i c a t e d by a loss of the initial stiffness and a r e d u c t i o n in the elastic limit of the muscle. The l a t e n c y r e l a x a t i o n w h i c h is induced i m m e d i a t e l y after the p r e c e d i n g changes in l e n g t h is augmented, r e l a t e d to the latency r e l a x a t i o n w h i c h is induced w i t h o u t the p r e c e d i n g changes in length. It remains u n c h a n g e d if the elastic limit of the muscle is not reached. F r o m the results it is c o n c l u d e d that l a t e n c y r e l a x a t i o n of skeletal muscle is not due to a d e t a c h m e n t of resting crossbridges. P h y s i o l o g i s c h e s Institut der U n i v e r s i t ~ t 2 H a m b u r g 13, G r i n d e l a l l e e 117

Hamburg

140

EVIDENCE FOR SHORTENING OF THE MYOSIN FILAMENT LENGTH IN THE SUPERCONTRACTIONS OF GLYCERINATED INSECT FIBRILLAR MUSCLE R. Graubner and R.A.Chaplaln Electronmicroscopy of vertebrate muscle during active muscle shortening has revealed substantial reductions in the length of the myosin filament (Frank, 1971; Herman and Dreizen, 1972). These experiments have been repeated under controlled conditions using glycerol-extracted flight muscle of the water bug Lethocerus colossicus. As a sensitive measure of the myosin filament length the distance between the cross-bridge origins was used. As shown first by Reedy, Holmes and Tregear (1965) this gives rise to the 145 ~ meridonal period in the X-ray diagram. In the present study changes in the 145 ~ period were recorded both from Optical transforms of electronmicrographs and with the aid of X-raydiffraction techniques. It could be,shown that when the fibres shortened by2o-25% in presence of Mg-ITP there was a change-over to a new period of 127 X. Under these conditions electronmicrographs of thin sections revealed the appearence of "triple-chevrons" instead of the "double-chevrons" normally seenin rigor muscle. In the electronmicrographs all cross-bridges appeared to be attaching to an actin filament. This finding is also supported by recordings of the density on the 59 ~ reflection. The apparent mass of myosin on the actln filaments was now 30-40% higher than in the rigor state of a slightly stretched fibre. Therefore a consideralbe molecular rearrangement in the superhelix of the myosin filament shaft must have taken place. The filament shortening is explained in terms of a torsional cross-bridge model (see BBRC 6], 738, 1974), in which the left-handed superhelix of cross-bridge origins along the myosin backbone undergoes a right-hand twist during contraction. As the result of this structural rearrangement all cgoss-bridge heads may find a binding place on the actin. Department of Biocyberneties, TH Otto von Guericke, Magdeburg, and Department of Physiology, Unlversity of Mainz, 65 Mainz, FRG

F~71 141 A LARGE INCREASE IN POTASSIUM CONDUCTANCE OF POISONED AND EXHAUSTED SKELETAL MUSCLE FIBRES R. Fink Frog sartorius muscles were stimulated in Ringer's solution at I Hz to induce complete mechanical exhaustion. The cable properties were determined with the conventional two micro-electrode technique and compared with those of normal fibres. It was assumed that the internal resistivity ( 1 7 0 ~ c m ; 20 oC) was not altered by the exhaustion procedure while the fibre diameter increased from 85 to 110 ~ m . The normal length constant ( ~ = 1.9 mm) diminished by more than 80% to 0.31 + 0.02 mm (n=10; 23 ~ in exhausted fibres. The most extreme c~ange was that in membrane resistance, which fell during exhaustion along a sigmoid curve from 3000 to 58.1 + ~.3 ~ c m 2 (n=1~; 23 oc) corresponding to a total conductance of 17200 ~ m h o / c m . The Cl-conductance gcl was reduced by using chloride-free sulfate or2sucrose solutions, g~ could then be calGulated as 14300 p mho/cm implying that gcl w~s only 2900 ~ m h o / c m ~. In nQrmal muscle gc' (200 p mho/cm 2) is greater than gK (130 ~mho/cm2). Experiments ' with gv-blocking ions (TEA and Rb) suggest that the increase in gK i~ due to an activation of both the delayed rectifier and, particularly, the 'slow' K-channel. Inward rectification also appe~+s to be present in exhausted fibres. An increased internal [Ca ], produced by CaC12injection or I-2 mE caffeine, lowered the input resistance of nor-mal fibres by 40 to max. 30%. This indicates that an increased [Ca2+]i may be at least partly responsible for the modified K-channel properties in exhausted muscle (Fink & LGttgau, J. Physiol. 2~4, 29P, 1973). Lehrstuhl Zellphysiologie, Ruhr-Universit~t, #63 Bochum, Postfach 142 RECEPTORS IN THE POSTSYNAPTIC MEMBRANE OF NORMAL AND DENEHYATED FROG SKELETAL MUSCLE FIBRES: THEIR REACTIONS TO ACh AND OTHER CHOLINERGIC AGONISTS F. l~eyer, Chr. Walther + and K. Peper Statistical analysis of voltage fluctuations (Katz and Miledi 1970, 1972) and of current fluctuations in voltage clamped muscle fibres (Anderson and Stevens 1973) yields both the amplitude and the duration of the underlying elementary conductance events produced by the interaction of molecules of different cholinergic agonists with the receptors of the postsynaptic membrane. We examined Acetylcholine (ACh), Carbachol (Carb), Succinylcholine (SOh), Decamethonium (deca) and Nicotine (nicot). While in the endplates of normal and den~rvated (21 aays) muscle fibres the mean conductance of a single ionic channel was about 71 = 21 p~-1 with no significant differences between the different drags, this value was reduced to about 72 = 9.5 p~-1 in extrasymaptio regions of denervated fibres. However, large differences in the closing time of open ionic channels were found; often the power spectra of current fluctuations in normal and denervated endplate regions could only be fitted by two components at low and high frequency. The two corresponding time-constants, T I and ~2 (ms) at 9~ are for ACh: 2.6, 7; Carb: 0.6, 3.1; SCh: 0.49, 5.3; decaz 0.26, 3.1; nicot: 0.25, 2.0~ respectively. The z-values at 23~ are about a factor 2 to 3 shorter. The simplest explanation of out results would be to assume that two receptor populations with different properties exist. 1. Receptors in the subsynaptic membrane with the properties 71 and ~I, 2. receptors outside of this region with the reduced y-valu@ and the prolonged time-constants. II. Physiologisches Institut der Universit~t des Saarlandes, D665 Homburg Saar, Germany; +Fachbereich Biologie, Universit~t Konstanz

R 72 143 k SURFACE CHARGE MODEL DESCRIBING THE EFFECTS OF Ca 2+, Mg 2+ AND H + ON THE CONTRACTION THRESHOLD OF FROG SKELETAL MUSCLE FIBRES Mari~e DSrrscheidt-K~fer and H. Pusch

The contraction threshold o f frog sartorius muscle fibres depends on [Ca~+~, ~ g ~o and 4 E ~ in a characteristic way (DSrrscheidt-K~fer, 1975). It has been concluded that H + acts by binding to fixed charged ~roups on the outer surface of the membrane, whereas the divalent cations mainly exhibit a screening behaviour; the surface potential, which is assumed to control the contraction threshold, is affected in both cases. To describe the results, a model has been developed in which sites are titrated by protons (Hille, Woodhull, Shapiro, d975). It is assumed that H + binds to two negatively charged sites ~ and ~ , which occu~ at a density of -0.0085e/~ 2 and -O.00~9e/~ 2 and have dissociation constants PEHI=2.0 and pKH2=#.I, and that H + dissociates - 2 from a positively charged site ~ with a density of +0.0028e/~ and a dissociation constant PKH~=8.5. The divalent cations Ca and ~g exert their effect on the contraction threshold by screenin~ the fixed charges; in addition it has to be considered that Ca ~+ binds to ~ and ~ to a small extent (K=2~M) to account for ~he results. The fit is satisfactory, except for the threshold values at pH ~.65 and pH ~0.~. For pH 6.5 and 0.5 mM Ca 2+ the model predicts a surface potential 9f_-92.5 mV and a free charge density of -0.0086e/~ (=-~e/(10.78~)2). The limitations and implications of the model are discussed. Lehrstuhl Zellphysiologie, Ruhr-Universit~t, @6~ Bochum, Postfach

144 9 Changes of Interstitial andVenous~'F], ~Ta.+], Ca++], [Mg++], [C1-], FPO~I Osmolality(OSM), Lactate ~%C1 Creatine ~ and Muscle Electroly~es =-' Due to Muscular Conctractions U. Tibes, E. Haberkorn, B. H e m m e r with the technical assistance of M. KStter and B. Arndt During passive movements of the rabbit hindlimbs f e m o r a l venous plasma (P1) and muscle lymph (ly} samples were a s s e s s e d for the tabulated variables (mean values +SE) before (I)~. during (H), and after (IH} superimposed cont r a c t i o n s which increased~_[~], ~PO~,n~ ~ac~ OSM and p a r t l y ~ r ~ m o r e in the L y than in the P1. T h e s e va~ab_Ies did notfl~eha:ga like in ~n u l t r a f i l t r a t e with Gibbs-Donnan corrections. ~ 1 ~ , FMg~, ~a+~ and F~a§ or less

satisfied these rules. Tissue electroly~es (mrnol/kg dry v~sigT1t)were only a l t e r e d in the contracting (c) but not in the passively (p) moved muscles. K+~, PI-I Ly-I PI-II LF-H PI-III Ly-III

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R78 145 CARDIAC AND RESPIRATORY PERIODICITIES IN VASOCONSTRICTORS OF BRAIN-INTACT AND PONTO-MEDULLARY CATS. M. Gregor, W. JEnig and L. Wiprich. The activity' in vasoconstrictors (vc) is modulated by cardiac and respiratory rhythms. The periodicities in these neurones are due to interactions in the brain stem of cardiovascular neurones, respiratory neurones, vagal afferents from the lung and baroaffelents. In order to get some insight into this interaction and into the central regulation of vasomotor activity these rhythmicities were analyzed for muscle and cutaneous vc to the hindlimb in brain-intact and pontomedullary (decerebrate) cats with respect to the cardiac (ECG) and the respiratory cycles (artificial respiration and phrenic activity) with neurophysiological methods. The following results were obtained: i) In brainintact cats cardiac and respiratory periodicities are more pronounced in muscle vc than in cutaneous vc. During hypercapnia a respiratory rhythm is visible in cutaneous vc which is otherwise very often undetectable. 2) Both periodicities are stronger in decerebrate than in brain-intact cats. In decerebrate preparations no difference exist between cutaneous and muscle vc. 3) The cardiac rhythm in the vc neurones is stronger during inspiration than during expiration. The results indicate that suprapontine brain structures exert an inhibitory influence on those neuronal pupulations in the lower brain stem which are responsible for the rhythmicities in the vasoconstrictor neutones. This inhibitory effect is especially pronounced for the cutaneous vc system and is responsible for the quantitati~ differences between cutaneous and muscle vc. Physiologisches Institut, Universitgt Kiel, 23 Kiel, Olshausenstr. 40/60. Supported by the Deutsche Forschu9~sgemeinschaft 146

THE INFLUENCE OF THE A M Y G D A L O I D COMPLEX ON C A R D I O V A S C U L A R PARAMETERS. K.H. Schl6r, H. Heidt, J. Buss, G. Stock The amygdala has been electrically stimulated either by bipolar steel electrodes or by coaxial bipolar steel electrodes in unr e s t r a i n e d awake as well as in pentobarbital anaesthetized cats. In the latter ones blood flow was measured in the abdominal aorta by means 6f an electromagnetic flow probe. S t i m u l a t i o n parameters in the range of 0,4-0,8 m A (40 cps, 0,5 msec pulse duration) applied to the central part of the amygdala induced an increase in arterial pressure (30 + 8 mm Hg), the peripheral r e s i s t a n c e being increased as shown by m e a s u r e m e n t s of the blood flow in ~he abdominal aorta. The effects could not be blocked by atropine (0.7 mg/ kg) but were abolished by phenoxybenzaminei(5 mg/kg) as well as b y p h e n t o l a m i n e (0.8 mg/kg). Electrical stimulation of the basolateral part of the amygdala (pars magnocellularis) elicited a decrease or a d e c r e a s e with a consecutive increase in arterial pressure and a m a r k e d increase in blood flow. This increase was in all probability m e d i a t e d by an active cholinergic v a s o d i l a t a t i o n and could be blocked by atropine (0.7 mg/kg). A n a e s t h e s i a did not qualitatively alter the changes in arterial pressure when the dosage of pentobarbital did not exceed 30 mg/kg i.p. The experiments clearly show that the amygdaloid complex contains functionally d i f f e r e n t structures as far as c a r d i o v a s c u l a r parameters are concerned. G. Stock, I. Physiologi'sches Institut der Universit~t, berg, Im N e u e n h e i m e r Feld 326

69 Heidel-

R74 147

CORTICAL NEURONAL ACTIVITY AND LOCAL BLOOD F L O W DURING EXPERIMENTAL CEREBRAL ISCHEMIA I/.-D. Heiss, A.G. Waltz and T. Hayakawa

To d e t e r m i n e t h e e f f e c t s o f i s c h e m i a on t h e f u n c t i o n o f i n d i v i d u a l n e r v e c e l l s we h a v e r e c o r d e d t h e a c t i v i t y o f i n d i v i d u a l c o r t i c a l n e u r o n s i n c a t s and r e l a t e d t h e a c t i v i t y t o c e r e b r a l b l o o d f l o w (CBF) i n t h e r e g i o n o f t h e n e u r o n b e f o r e and a f t e r o c c l u s i o n o f one m i d d l e c e r e b r a l a r t e r y (MCA). The a c t i o n p o t e n t i a l s were r e corded extracellularly w i t h g l a s s m i c r o e l e c t r o d e s , CBF was m e a s u r e d b y h y d r o g e n - p o l a r o g r a p h y w i t h p l a t i n u m e l e c t r o d e s 125 i n d i a m e t e r . No c o n s i s t e n t c h a n g e s o f u n i t a r y a c t i v i t y w e r e n o t e d w i t h c h a n g e s o f MABP i n t h e r a n g e o f 58 t o 210 mmHg. C h a n g e s o f CBF p r o d u c e d by c h a n g e s o f PaC02 i n t h e r a n g e o f 25 t o 66 mmHg likewise did not result in consistent changes of neuronal activit y . I m m e d i a t e l y a f t e r MCA o c c l u s i o n a b n o r m a l p a t t e r n s o f n e u r o n a l activity included bursts; prolonged, high-frequency repetetive discharges; i n c r e a s e s o f f r e q u e n c y ; d e c r e a s e s o f f r e q u e n c y ; and cessation of activity. I n c r e a s e s o f CBF a f t e r i n i t i a l marked d e c r e a s e c o u l d be a c c o m p a n i e d b y r e s u m p t i o n o f u n i t a c t i v i t y . Freq u e n c y o f t h e n e u r o n a l a c t i v i t y u s u a l l y was l e s s t h a n b e f o r e o c c l u s i o n . No a c t i v i t y was d e t e c t e d i n r e g i o n s w i t h c a l c u l a t e d CBF v a l u e s o f l e s s t h a n 0 . 1 8 m l / g . m i n . The r e s u l t s show t h a t t h i s value is critical f o r p e r s i s t e n c e o f n e u r o n a l a c t i v i t y and i n d i c a t e r e g i o n s o f b r a i n can be a s s o c i a t e d w i t h t h e r e s u m p t i o n o f the activity of neurons. Hirnkreislauflaboratorium der Neurologischen Universit~tsklinik Wien, L a z a r e t t g a s s e 14, A - 1090 Wien 148 THE EFFECT OF HYPOXIA ON THE J REFLEX Experiments

Jasleen Ahluwalia Mishra

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R 75 149 INVESTIGATION THE W, S c h r o e d e r

SURE AND

ON THE RELATION BETWEEN INTRACORTICAL OXYGEN PRESELECTROCORTICOGRAM IN CATS. P. Alf, K. O f f e n l o c h , a n d G. Z a h n e r

In 11 c a t s p l a c e d i n a s t e r e o t a x i c instrument under barbiturate anesthesia the laminar intracortieal pO 2 profiles were measured with Pt-microelectrodeso Also the relatlonship between changes of the intracortical pO o and of the electrocortieogram (ECoG) was investigated. The P~-mieroelectrodes (tip d i a m e t e r l-2~u) were coated with a membrane of polystyrol, and had a nearly horizontal polarographic p l a t e a u w i t h i n a r a n g e o f a p p r o x . 775 to 825 mV. Measurements and calibrations were done with a voltage of 800/mV. The ECoG was AC-recorded with gold electrodes placed on the exposed cortical surface. In a series of experiments the laminar pOe-profiles were investigated. The lowest pC^ values were found-at cortical depths between 500 and 1500~.ZHigher pO 2 v a l u e s w e r e f o u n d t o w a r d s t h e s u r f a c e o f t h e c o r t e x as w e l l as towards the white matter. The intracortieal p O 2 r a n g e d f r o m I to 35 T o r t . F o r c o m p a r i s o n with the ECoG the pO 2 values mostly of lO00/u depth were taken. Pharmacologically induced changes of the electrographic patterns were not always correlated with changes of t h e p O ~ , a n d g e n e r a l l y speaking, no consistent relationship between tSe intraeortieal pO 2 and the ECoG was found. Neurophysiologisches Laboratorium und Abteilung ftir A n g e w a n d t e Physiologie, Zentrum der Physiologie, J.W. Goethe - UniversitHt, D-6 Frankfurt am Main, Theodor Stern Kai 7

150 RESPONSE OF MICROFLOW AND LOCAL TISSUE Pc 2 OF BRAIN CORTEX TO DIRECT ELECTRICAL STIMULATION. E. Leniger-Follert and D. W. L0bbers Microflow and local tissue Pc_ of brain cortex were recorded simultaneously and continuously by a surface element which contained two or four lOO/um or 50/um Pt-wires for the registration of microflow and in a distance of about 150/~im two 15/um Pt-wires for the measurement of local Pc^. Direct electrical stlmulation p~oduced an increase of mlcroflow at all sites in the stimulated brain area. The increase of microflow occurred after a defined threshold of the stimulation parameters had been reached. The size of the increase of microflow was dependent on the size of the stimulation parameters, until a maximal microflow was reached. The increase of microflow already began during the stimulation and reached its maximum after the end of the stimulation. Then microflow gradually returnedto its initial level within a few minutes. The time for reaching the initial value depended on the size of the preceeding stimulation. Parallel to the increase of microflow local tissue Pc 2 increased and reached its maximum during the maximum of microflow and then also returned to preceeding values. There was no initial decrease of Pc 2 if microflow increased. In some cases microflow initially decreased for some seconds with the begin of stimulation but then also increased during stimulation as in the other cases. Parallel to the initial decrease of microflow local Pc 2 dropped down and then again increased with increasing microfl0w. It is concluded that the increase of microflow is triggered by an increase of metabolism induced by the electrical stimulation. Furthermore, the increase of microflow occurred mostly so rapidly and so strongly that local Pc 2 even increased although the oxygen demand is augmented. This Pc 2 increase is necessary to produce a higher Pc 2 gradient. In those cases in which microflow initially decreased, there wasobviously a constriction of arterioles which was then afterwards overwhelmed by metabolic factors. Max-Planck-Institut for Systemphysiologie, D-46 Dortmund, Rheinlanddamm 201

R 76 151

~O~ONEURONALA~IVITYOFC~E~ALCORTICAL~ICES~INTAIN~ZNVITRO U.Kuhnt Slices (3,50-400 m thick) were cut in the frontal plane from guinea pig cortex, and were placed in a tissue c h e e r similar to that described by Yamamoto(Exp. Brain Res.14,425-435,1972).One stimulating electrode was inserted into the white matter just below the recording area, and a second one in the grey matter either lateral to the recording electrode or above it in layer I/II.Zhe slices could be kept in good condition for up to 9 hours.Yieldpotentials as well as extra- and intracellular potentials were recorded from all layers of the grey matter.Penetrated cells showed typical injury discharges but there was no clear evidence of spontaneous spike activity:if the membrane potential stabilised, the frequency of the spike activity decreased(to less than 0.1 Hz in most eells).Stimulation of the white matter evoked in some cells an activation pattern consisting of excitation followed by inhibition of different lengths (up to $00 mseo) and different amplitudes (up to 15 mV).In two of these cells the cmrplitude of the initial EPSP depended on th~ stimulus strength until firing threshold was reached.Some of these cells could be activated antidromically as well.Other cells, which could not be activated orthodromioally showed antidromic responses, even with very low stimulus intensities.Lateral stimulation often showed a similar activation pattern, but the initial EPSP often did not reach threshold.Primary inhibition due to lateral stimulation was only obse~ed once.Up to now multiple spike responses were observed only in extracellular recordings. ~PI f~r biophysikal ieohe Chemie,o-$g G~ttingen-Nikolausberg 152 STEP-WISE AND CONTINUOUS DISCHARGE OF la MUSCLE SPINDLE AFFERENTS DURING SLOW RAMP STRETCHES OF TRICEPS SURAE MUSCLE. 0. Haeggqwist, K. Takano and F. Kirchner The firing rate of Ia muscle spindle afferents of the M. triceps surae was recorded during ramp-and-hold stretches at velocities between 250 and 0.05 mm/sec on anaesthetized cats (chloraloseurethane), deefferented from L5 to $I or curarized with a high dose. We observed two types of firing pattern at slow stretches. One type showed a continuously increasing spike frequency and the other a step-wise increase of spike frequency up to five steps. The frequency steps appeared to be equal at different stretch velocities. The lower frequency steps were related to the length of the muscle at low stretch velocities. With higher velocity additional steps occurred towards the end of the ramp. We explain the results by the following hypothesis: The spike frequency is governed by the summation of generator potentials of the endorgans of single intrafusal fibers which converge onto a single afferent nerve fiber. A step-wise frequency increase might be due to different slackness of the intrafusal fibers at normal length. The single endorgan might show a saturation effect during the ramp stretch. On the other hand, the continuous increase of the spike frequency could be produced in nerve fibers connected to characteristically similar endergans. Physiologisches Institut der Universit~t G6ttingen, Lehrstuhl II, D 34 G6ttingen, Humboldtallee 7

R 77 153

C h a n g e s of N[uscle Spindle A c t i v i t y d u r i n g S i m u l t a n e o u s R e l e a s e of Neck and L a b y r i n t h i n e R e f l e x e s U. H e i d e n r e i c h and S.S. Sch~ifer T h e s p o n t a n e o u s a c t i v i t y of p r i m a r y m u s c l e s p i n d l e e n d i n g s of the NI. g a s t r o c n . (cats) w e r e r e c o r d e d d u r i n g n e c k a n d l a b y r i n t h i n e r e f l e x e s r e l e a s e d s i m u l t a n e o u s l y by r o t a t i n g the h e a d to the r i g h t and to the left side by 90 ~ out of the n o r m a l p o s i t i o n and by d o r s i f l e c t i o n . A f t e r each m o v e m e n t out of the n o r m a l p o s i t i o n the h e a d w a s l e d back into the n o r m a l p o s i t i o n . E a c h new r o t a t i n g m o v e m e n t took p l a c e o n l y ff the r e s p e c t i v e t e r m i n a l p o s i t i o n of the h e a d was kept f o r 50 see. The s p i n d l e s showed d u r i n g the r o t a t i n g m o v e m e n t p h a s i c and d u r i n g the t e r m i n a l p o s i t i o n of the h e a d t o n i c a c t i v i t y c h a n g e s which w e r e q u a l i t a t i v e l y e q u a l in d e p e n d e n c e on d i r e c t i o n of head m o v e m e n t . T h e s p i n d l e a c t i v i t y i n c r e a s e d d u r i n g a l l m o v e m e n t s that led the head out of the n o r m a l p o s i t i o n . F o r t h i s the a c t i v i t y w a s c o m p a r e d with the i n i t i a l a c t i v i t y i. e . , the d i s c h a r g e f r e q u e n c y o c c u r r i n g b e f o r e the b e g i n n i n g of head m o v e m e n t . T h e i n c r e a s e in a c t i v i t y l a s t e d o v e r 35 s e c a f t e r b e g i n n i n g of head m o v e m e n t . T h e n it d e c r e a s ed a g a i n s t i l l d u r i n g the t e r m i n a l p o s i t i o n on to the v a l u e of i n i t i a l a c t i v i t y . By m o v i n g the h e a d into the n o r m a l p o s i t i o n the s p i n d l e a c t i v i t y was not i n f l u e n c e d m a r k e d l y . T h e c h a n g e s of s p i n d l e a c t i v i t y a r e t r a c e d back to a s y n c h r o n o u s change of f u s i m o t o r a c t i v i t y . It s h a l l be d i s c u s s e d ff the r e f l e x b e h a v i o u r of the l u m b a r g a m m a m o t o n e u r o n e s that c o n t r a s t s to the r e f l e x l y i n d u c e d m o v e m e n t s of the 4 l i m b s d e s c r i b e d h i t h e r t o can be e x p l a i n e d by p r o p e r t i e s of the vestibular neurones. I n s t i t u t ftir n o r m a l e u n d p a t h o l o g i s c h e P h y s i o l o g i e , Universit~it K61u, D-5000 K61n, R o b e r t - K o c h - S t r a f ~ e 39 154 INHIBITION OF E X T E N S O R F U S I M O T O R NEURONS BY A N T A G O N I S T I C M U S C L E SPINDLE A F F E R E N T S Chr. Fromm, J. N o t h and A. T h i l m a n n In the d e c e r e b r a t e cat, about the half of f u n c t i o n a l l y isolated and identified y efferents (14-48 m/sec) to the m e d i a l gastrocn. m u s c l e w e r e c o n s i d e r a b l y inhibited by longitudinal v i b r a t i o n (at 15-1OO ~m, 1OO-3OO Hz) applied to the tendons of the n o n - c o n t r a c ting p r e t i b i a l flexors EDL and TA. A sigmoid r e l a t i o n b e t w e e n the d e g r e e of i n h i b i t i o n and the amplitude of v i b r a t i o n was obtained: a d e c r e a s e in fusimotor d i s c h a r g e rate appeared at 15-25 ~m and was g r e a t e s t at 1OO ~m amplitude. On i n c r e a s i n g the f r e q u e n c y of v i b r a t i o n the i n h i b i t i o n increased proportionately. R e g a r d i n g the o c c u r r e n c e and degree of i n h i b i t i o n the f u s i m o t o r r e s p o n s e s to m u s c l e v i b r a t i o n c o r r e s p o n d e d w i t h those to afferent t e t a n i z a t i o n of the d e e p p e r o n e a l nerve at a strength o f 1.2 - 1.4 times thresh. g r o u p I. C u t t i n g the nerve supply of the p r e t i b i a l flexors completely abolished the v i b r a t o r y reflex responses. The a n t a g o n i s t i c i n h i b i t i o n of extensor y m o t o n e u r o n s can be m o s t likely a t t r i b u t e d to e x c i t a t i o n of p r e t i b i a ! primary spindle endings by vibration. In addition, an action of p r e t i b i a l group II afferents on extensor y efferents was r e v e a l e d both by a m a r k e d increase in i n h i b i t i o n d u r i n g peroneal nerve s t i m u l a t i o n at strengths above the group I range as w e l l as by comparing the fusimotor responses to v i b r a t i o n and to stretch (8mm) of the p r e t i b i a l flexors. The d e s c r i b e d reflex pathways obey the p r i n c i p l e of s-y-linkage. P h y s i o l o g i s c h e s Institut, L e h r s t u h l II, U n i v e r s i t ~ t D~sseldorf, D-4OOO DHsseldorf, Moorenstr. 5

R 78 155 D E C R E A S E O F THE R E C U R R E N T I N H I B I T I O N OF E X T E N S O R M O T O N E U R O N S DUE TO GROUP: II~ A F F E R E N T INPUT Chr. From/n, J. H a a s e and E. Wolf In d e c e r e b r a t e cats 21 m o t o n e u r o n s r e s p o n d i n g t o n i c a l l y to gastrocnemius nerve t e t a n i z a t i o n were isolated in v e n t r a l root f i l a m e n t ~ The effects of v a r y i n g the a f f e r e n t fiber input on the r e c u r r e n t inhibition (Fn-F i) were studied either by i n c r e a s i n g the e l e c t r i cal stimulus s t r e n g t h from 1.5 to 12 times g r o u p I t h r e s h o l d (TI) or by v i b r a t i n g triceps surae (1OO ~m) at 150 Hz o r t h o d r o m i c freq u e n c y and at c o n s t a n t a n t i d r o m i c stimulus parameters. F n and F i were d e f i n e d a c c o r d i n g to R. G r a n i t et al. (J. Physiol. 154, 308, 1960). The m e a n r e c u r r e n t i n h i b i t i o n (Fn-F i) was g r e a t e s t d u r i n g selective a c t i v a t i o n of Ia afferents by v i b r a t i o n , b e i n g 2.3 times greater than Fn-F i d u r i n g nerve t e t a n i z a t i o n at 1.8 T I. Fn-F i d e c r e a s e d by some 50 % b e t w e e n 1.8 T I and 8 T I. The d e p e n d e n c e of F n on a f f e r e n t fiber input was less uniform, a l t h o u g h it did show a s l i g h t t e n d e n c y to i n c r e a s e w i t h i n the g r o u p II range. In several e x p e r i m e n t s further m o t o n e u r o n s were r e c r u i t e d w h e n stimulus s t r e n g t h was r a i s e d so as to e x c i t e g r o u p II afferents. A d i s i n h i b i t o r y action of g r o u p II a f f e r e n t s on e x t e n s o r m o t e n e u rons by r e d u c i n g the R e n s h a w i n h i b i t i o n is suggested. This w o u l d r e c o n c i l e the c o n t r a d i c t o r y v i e w s on the h y p o t h e s i s that the seco n d a r y endings c o n t r i b u t e e x c i t a t i o n to the tonic stretch r e f l e x in the d e c e r e b r a t e cat (G.J. M c G r a t h and P.B.C. Matthews, J. Physiol. 235, 371, 1973; O . P o m p e i a n o et a l . , B r a i n Res.6_~6, 519, 1974). P h y s i o l o g i s c h e s Institut, L e h r s t u h l D-4OOO D~sseldorf, Moorenstr. 5 156 EXCITATORY THE M U S C L E

REFLEX RESPONSES THEY INNERVATE

II, U n i v e r s i t ~ t

DUsseldorf,

OF F U S I M O T O R N E U R O N S TO V I B R A T I O N Chr. F r o m m and J. N o t h

OF

An i n h i b i t o r y action of v i b r a t i n g triceps surae on 25% of the y efferents to g a s t r o c n e m i u s m u s c l e was d e s c r i b e d r e c e n t l y (Chr. Fromm, J. Noth, Brain Res. 83,495, 1975). Of 63 y e f f e r e n t s (19-44 m/sec) i n v e s t i g a t e d in d e c e r e b r a t e cats a b o u t 40% r e s p o n d e d to triceps v i b r a t i o n (200 Hz, 1OO ~m) w i t h an i n c r e a s e (3-45 imp/sec, mean: 12.7 imp/sec) in d i s c h a r g e rate. These units w e r e d i s t i n g u i s h e d from those i n h i b i t e d by v i b r a t i o n by their w e a k e r s u s c e p t i b i l i t y to a n t i d r o m i c i n h i b i t i o n and by their e x c i t a t o r y r e s p o n s e to m u s c l e stretch. T h r e s h o l d a m p l i t u d e of f u s i m o t o r r e f l e x was 20 ~m for vibration. On r a i s i n g the v i b r a t i o n a m p l i t u d e the t o n i c f u s i m o t o r f a c i l i t a t i o n - often o u t l a s t i n g the v i b r a t i o n period - i n c r e a s e d up to 1OO-150 ~m, in p a r a l l e l w i t h the tonic v i b r a t i o n r e f l e x of e efferents. It was c o n f i r m e d that the r e f l e x arose from r e c e p t o r s within the v i b r a t e d muscle, but not from p r e s s u r e - p a i n r e c e p t o r s of the A c h i l l e s tendon, w h i c h can evoke f u s i m o t o r r e f l e x e s on s q u e e z i n g or p u l l i n g the tendon. Therefore, Ia a f f e r e n t s are thought to be m o s t likely r e s p o n s i b l e . An a u t o g e n e t i c e x c i t a t i o n of y m o t o n e u r o n s by Ia fibers was also o b s e r v e d in the spinal cat b e f o r e and after Dopa injection. Some features of this r e f l e x p o i n t e d to a p o l y s y n a p t i c spinal p a t h w a y o r g a n i z e d in an e - y - l i n kage. The s i g n i f i c a n c e of a p o s i t i v e f e e d b a c k onto y m o t o n e u r o n s has to be c o n s i d e r e d in c o n n e c t i o n w i t h s t a b i l i t y in the stretch reflex. P h y s i o l o g i s c h e s Institut, L e h r s t u h l D - 4 O O O D~sseldorf, Moorenstr. 5

II, U n i v e r s i t ~ t

DUsseldorf,

R 79 157

BEHAVIOUR OF LUMBARRENSHAWCELLS AND IA-INHIBITORY INTERNEURONESDURINGEXCITATION OF MUSCLESPINDLES~y i~EANSOF SUCCINYLCHOLINE H.D. Henatsch, R. Beneckeand Ch. Hellweg~J I.v. administration of Succinylcholine (SCh 0.5-I mg/kg) induces strong excitation of muscle spindle afferents which in turn cause reflex discharges of mainly small tonic ~-motoneurones (MN) (Henatsch u. Schulte, 1958: PfIUgers Arch. 267, 279-294). We have studied, in anesthetized or decerebrate cats, the behaviour of microrecorded Renshaw cells (RC) and la-inhibitory interneurones (la-IN) belonging to the GS-pool. Afferent inflow was restricted to the nerves from triceps surae. Results: The antidromic early responses of all tested RC remained uninfluenced ~ C h administration. In anesthetized cats, spontaneous RC activity was neither changed nor newly induced under SCh, although small ~-MNwere usually activated for up to 2 min after the injection. Stretch-induced RC activity was slightly enhanced, la-IN showed the expected increase of activity lasting up to several min. In decerebrate preparations, SCh induced usually a short-lasting period (about 30 sec} of increased or newly appearing spontaneous RC activity. Concomitantly, large ~-MNdischarges often appeared in addition to strongly enhanced activity of small a-units. Strong stretch-induced responses of RC, of tonic character, were now obtained~ The frequency increase of la-IN after SCh was delayed during the period of RC firing. - I t is concluded that the main recurrent input to RC originates from large rather than small tonic ~-MN. Only i f the large units take up tonic firing, the RC show enhanced and tonic activity and are capable of counteracting the excitation of Ia-IN to which they are synaptically connected. D@pt. of Physiolo~y I f , Univ. of G~ttingen, D 34 G~ttingen, Humboldtallee 7 +J now at Max-Planck-lnstitute for Biophysical Chemistry, G~ttingen 158 THE EFFICIENCY OF THE SYNAPSES BETWEEN SINGLE MUSCLE SPINDLE AFFERENTS AND DORSAL SPINO-CEREBELLAR TRACT NEURONS O.-J. GrUsser and J. K r ~ l l e r The action p o t e n t i a l s of s i n g l e DSCT-neurons were recorded in s p i n a l i z e d cats by means of tungsten microelectrodes. For the present study the responses of one class of DSCT-neurons r e c e i v i n g e x c i t a t o r y a f f e r e n t s only from the gastrocnemius muscle spindles were selected. A f t e r i d e n t i f i c a t i o n by e l e c t r i c a l microstimulation s i n g l e axons with e x c i t a t o r y synapses at the recorded DSCT-neuron were i s o l a t e d by microdissection. Periodic and random e l e c t r i c a l stimulus t r a i n s were applied to the axon, in order to study the signal t r a n s f e r between the presynaptic and postsynaptic neuron. The synaptic signal t r a n s f e r depended on the average impulse rate in the presynaptic axon. In other experiments simultaneous recordings of the impulse t r a i n of a postsynaptic DSCT-neuron and a s i n g l e muscle spindle a f f e r e n t connected with the DSCT-neuron were obtained. By applying mechanical s t i m u l i to the gastrocnemius muscle the average impulse rate of the a f f e r e n t input was v a r i e d . From the auto- and crosscorrelograms of the presynaptic and postsynaptic impulse t r a i n the e f f i c i e n c y of the synapses formed by a s i n g l e a f f e r e n t f i b e r was studied. The i n f o r m a t i o n - t h e o r e c t i c a l analysis of the data is presented in the paper by Eckhorn et a l . at t h i s congress.

Supported by the Deutsche Forschungsgemeinschaft (Gr 161). Physiologisches I n s t i t u t der FU B e r l i n , D-I B e r l i n 33, Arnimallee 22.

R 80 159

O O ~ A R I S O N BETWEEN THE AO~I~s OF S~LTLTANEOUSLY RECORDED HUF~N MOTOR UNITS FROM THE GASTROCNEMIUS AND SOLEUS MUSOLES V. Dietz and H.-J. Freund Recemt investigations of motor unit activities f~om humam hamd muscles, supported the hypothesis, that their fumctional characteristics are determined by the graded excitability of motomeutones according to size (Freund et al. J.Neurophysiol.in press, 1975). The present experimemts on two synergistic but fumctionally and histochemically different calf muscles should prove whether they show a similar relationshipor rather a distinctio~ between a tonic and phasic type as suggested by animal experiments. One soleus and one gastrocnemius motor unit were recorded simultaneously by two electrodes durimg various motor tasks including tonic a~d phasic contractions.Only quantitative differences betweem the units of the two muscles could be observed: O~ the average, soleus units were earlier recruited a~d showed a larger firing rate modulation. All units could be activated tonically and phasically. No evidence was found indicating the existence of two qualitatively differentpopulations of cells. High or low threshold units of both muscles showed more similarities than low and high threshold units of one muscle. The results closely resemble therefore those obtained from hamd and forearm muscles. She mai~ difference between human forearm and calf muscles is the significamtly lower firing zates of the latter. Neurol.Univ.-Klinik m.Abtlg.f. Neurophysiologie D 78 Freiburg i. Br., Ha~sastraBe 9 160 PROJECTION FROMNECKAFFERENTSTO HINBLIMB MOTONEURONES. Pc Kenins, Ho Kikillus and E.D. Schomburg With intracellular microrecording and monosynaptic reflex testing the effects of electrically stimulated neck afferents upon hindlimb motoneurones (PBSt, ABSm, G-S, FDL, PL, Tib., Per.) were investigated in cats under three different conditions: l) intact, anaesthetized with chloralose/urethane 2) precollicular decerebrate 3) spinalized at CI. Bipolar stimulation was performed with trains (2-6 impulses, 50-I00 Hz) at th~ dorsal cutaneous nerves (CI-CR), the muscle nerve to the dorsal neck extensors (CI-CR) and the spinal ganglion (CI, C2) which presumably included stimulation'of~intervertebral joint afferents. In intact cats ipsi- and contralateral stimulation of cutaneous and medium to high threshold muscle afferents and of the ganglion caused a highly variable facilitation of all tested lumbar motoneuronal pools (minimum latency 20 msec, duration about 30-I00 msec). This effect is abolished by decerebration and spinalization. Presumably i t involves, a cortical loop (Abrahams, J. Physiol. 215, 755, 1971)o The SBS reflexes evoked by stimulation of the sural, tibial or peroneal nerve were markedly depressed by stimulation of the neck afferents. In decerebrate cats stimulation of ipsi- and contralateral cutaneous and muscle afferents produced either no response, or a late facilitation or inhibition (onset about lO0 msec, duration 150 msec) varying between animals~ Stimulation of the ganglion could evoke a short latency facilitation (5-8 msec) in lumbar motoneuronal pools~ This short latency effect, which could not be seen in intact cats, persisted after spinalization. We assume that i t is evoked by intervertebral joint afferents and that i t forms the basic pathway for the neck reflexes. Dept. of Physiology I I , Univo of G~ttingen, D 34 G~ttingen, Humboldtallee 7

R 81 161

FREQUENCY RESPONSE OF RENSHAW CELLS

S. Cleveland and H.-G. Ross

Sinusoidally modulated trains of impulses, produced using a voltage-controlled generator, were applied to cut ventral roots (L7 or $I) of intercollicular decerebrate, deafferented cats in order to determine the frequency response (gain and phase) of Renshaw cells (n=20). Modulation frequencies ranged between 0.2 and about 50 Hz. Each sinewave period was d&vided into a number of bins and the average number of Renshaw cell spikes per bin was calculated. On the average, the gain of the Renshaw cells rose slowly with increasing modulation frequency (about 3 dB/octave), while the phase lag became greater. Gain was roughly proportional to generator modulation depth within the range tested (up to 30 %). Another indication of the Renshaw cells" linearity is the relatively low harmonic distortion (< 10 %). Alternatively, the responses of Renshaw cells to step changes in input signal were used to compute the frequency response: the results when either stimulus frequency or the number of ~ motor axons activated changed suddenly were similar. The apparent lack of rate-sensitivity in spinal e motoneurons (POPPELE and TERZUOLO, Science 159, 743, 1968) -- in contrast to the highly rate-sensitive motoneurons of the eye muscles (DALEY and BARMACK, Kybernetik 15, 39, 1974), which are known to be without recurrent inhibition (SASAKI, Jap. J. Physiol. 13, 287, 1963) -- could be explained by the characteristics of Re-nshaw cells revealed by our experiments. Physiolog.

Institut

(Lehrstuhl II) D-4 D~sseldorf, Moorenstr.

5

162 EFFECT OF TETANUS TOXIN ON THE ANTAGONISTIC INHIBITION AFTER INTRA-MUSCULAR APPLICATION OF THE TOXIN. K. T a k a n o a n d F. K i r c h n e r

Excitatory effect of tetanus toxin on the motor system is believed to be due to its blocking action on inhibitory mechanisms. Some inhibitory mechanisms appear to persist in local tetanus e.g.from Renshaw cell to Renshaw cell and to Ia inhibitory interneuron (Pfl~gers Arch. 355, R 90, 1975) and on the gamma-system (NaunynSchmiedeberg's Arch. Pharmacol. 276, 421, 1973). Therefore it seems necessary to study the effect of tetanus toxin on the inhibitory mechanisms on the motoneuron after i.m. application in view of the fact that the toxin, after reaching the spinal cord, concentrates around the motoneurons (Habermann, E.; WellhOner, H., Klin. Wschr. 52, 255, 1974). The monosynaptic reflex in response to the test stimulus on the nerves to the gastrocnemius muscle was recorded from the divided ventral root L7. Conditioning inhibitory stimulus was given to the ipsilateral peroneal nerve. The maximal inhibitory effect of about 50 % at the conditioningtest-stimulus interval of about I msec did not change during the period of 24 - 50 h after the toxin application. There is a possibility that tetanus toxin does not affect the antagonistic inhibition on the alpha motoneuron in the natural disease. Physiologisches D 34 G6ttingen,

Institut der Universit~t G6ttingen, Humboldtallee 7

Lehrstuhl

II,

R 82 163 S E P A R A T I O N Os A SMALL POOL OF H I G H L Y L A B E L L E D V E S I C U L A R C O M P O N E N T S A F T E R E L E C T R I C A L S T I M U L A T I O N OF THE T O R P E D O E L E C T R I C ORGAN. H.Zimm e r m a n n and R . R . B a k e z On zonal c e n t r i f u g a t i o n synaps v e s i c l e s can be i s o l a t e d from the e l e c t r i c organ of T o r p e d o on a Sucrose g r a d i e n t a s a d e f i n e d peak showing o v e r l a p p i n g a c t i v i t i e s of a c e t y l c h o l i n e (ACh) and ATP.Inc o r p o r a t i o n of r a d i o a c t i v e ACh into s y n a D t i c v e s i c l e s from large pieces of e l e c t r i c organ p e r f u s e d ~ i n V i t r o w i t h ~ 4 C ~ a c e t a t e is ~" g r e a t l y e n h a n c e d by low f r e q u e n c y s-{im---ui~tion (6-12/min)of the a t t a c h e d nerve. Low f r e q u e n c y s t i m u l a t i o n does not alter vesicle numbers. The s p e c i f i c r a d i o a c t i v i t y of ACh is lowest in the peak c~ v e s i c l e b o u n d ACh and increases by a factor of 4 to i0 towards a peak in the h e a v i e r sucrose c o n t a i n i n g only 10-15% of peak tube ~ h . Lactate d e h y d r o g e n a s e , c h o l i n e a c e t y l t r a n s f e r a s e , t o t a l e s t e r a s e and P r o t e i n d i s t r i b u t i o n did not p a r a l l e l the curve of specific labelling and showed peaks in the soluble and h e a V v m e m b r a n e fractions. If ~ H ] - a d e n o s i n e is applied s i m u l t a n e o u s l y the d i s t r i b u t i o n o f [ 3 ~ label p a r a l l e l s that of labelled ACh i n d i c a t i n g i n c o r p o r a t i o n of adenosine into the s a m e p o o l as acetate. High frequency restimulation (5/sec) in the p r e s e n c e of iOO ~LM c a r b a m y l c h o l i n e to inactivate the p o s t s y n a p t i c side leads to a r~lease of both isotopes w h i c h can be c o l l e c t e d in the perfusate. From the data o b t a i n e d it is c o n c l u d e d that a small v e s i c u l a r pool s e p a r a b l e from the bulk of the v e s i c l e s shows a high t u r n o v e r of both ACh and n u c l e o t i d e on stimulation. R e s t i m u l a t i o n leads to a release of ACh and n u c l e o t i d e into the perfusate. D e p a r t m e n t of N e u r o c h e m i s t r y , M a x Planck I n s t i t u t fHr B i o p h y s i k a l i sche Chemie, D-34 G~ttingen, A m FaBberg. 164 METABOLICALLY INDUCED CONVERSION OF BEATING TO BURSTING PACEMAKER ACTIVITY IN ISOLATED APLYSIA NEURONS R.A. Chaplain and G. Kr~mer With Rq-R.. neurons from Anlvsia californica, isolated from their synaptic ephaphtic and humoral inputs~ it has been demonstrated that conversion of the regular beating frequency to bursting discharge pattern can be induced by certain cell metabolites. The addition of activators of the neuronal phosphofructoklnase (PFK): fructose-6~phosphate (F-6-P) or its nonmetabolizable analogue I-deoxyF-6-P and cyclic 3~5'AMP proved particularly effective. While 3:5'AMP induced bursting activity in all R~-R]3 neurons, with F-6-P and deoxy,F-6-P this was only true of R3, R~, R~ and R|! pacemaker cells. With another activator of the phosphpfructoklnas~ 5'AMP only double spikes could be elecited in R 7 and R^ neurons. A similar observationwas obtained on the R. cell with 3-~hospho~lycerate (3-PGA), an activator of the neuronal frucIO . . . . tose-],6-dlphosphatase (FDPase). However, 5'AMP at hlgher concentratlons inhlblts the FDPase in these neurons and hence the formation of the F-6-P through gluconeogenis, while 3-PGA becomes inhibitory for the PFK. In these cases reciprocal control of the PPK-FDPase may preclude sufficiently high activity of the PFK. A tendency for burst-like discharges could also be obtained with the gluconeogenic substrates citrate, pyruvate and -ketoglutarate, The induction of the bursting discharge pattern characteristic for the descri++ + bed PFK activators could not be duplicated either by low Ca and/or high K media nor by artlfidal shifts in membrane potential triggered by dspolarizing and hyperpolarizing currents. Department of Physiology, University of Mainz, D 65 Mainz, Obere Zahlbacher Str. Germany Supported by the Deutsche Forschungsgemeinschaft, Ch 25/I.

R 83 165 THE EFFECT OF CELLULAR METABOLITES ON PENTYLENETETRAZOL-INDUCED DOUBLE AND TRIPLE SPIKESINISOLATEDAPLYSIA.PACEMAKER.NEURONS. G..Kr~merandR.A. Chaplain Regularly beating pacemaker neurons can be isolated completely free of all synaptle, ephaptic or humoral inputs. Socalled R3-R]4 neurons isolated from A~.~sia californica can be induced to discharge spike doublets and triplets or even paroxysmal depolarizations are observed. PTZ causes initially the following effects: increase in spike density, reduction in both spike overshoot and postspike hyperpolarlzation, prolongation of spike duration. While in two-thlrds of all neurons the characteristic double spikes develop within 30 min following PTZ administration, the remainder of the neurons depolarize by 10-20 mV and all rhythmic activity ceases. However, when the PTZ concentration in the medium is lowered the latter neurons equally start to discharge double spikes. The occurrence of spike triplets is related to a progressive reduction in the amplitude of the second spike, which can, ~owever, increase again once the tripl&tpattern has become manifest. The PTZ-induced changes in impulse discharge pattern revert t o single spikes in presence of characteristic metabolites which either directly slow the oscillatory enzyme activity driving the rhythmic spike discharges (such as ATP or 3-phosphoglycerate), or provide substrate precursors for the inhibitory modifiers (such as lactate, pyruvate or glutamine). In contrast pentobarbital, phenobarbital or diphenylhydantoin unspecifically prevented all further spike activity in PTZ-treated as well as normal pacemaker neurons. It appears therefore likely that PTZ and the metabolic modifiers act on a common regulatory site of the intraneuronal mechanism governing the rhythmic spike activity. Supported by the Deutsche Forschungsgemeinschaft, Ch 25/I Department of Physiology, Universityof Mainz, D-65Mainz, Obere Zahlbacherstr.67 166 FREQUENCY-SETTING OF BEATING APLYSIA PACEMAKER NEURONS BY MODIFIERS OF PHOSPHOFRUCTOKINASEANDFRUCTOSE 1,6,DIPHOSPHATASE R.A.ChaplainandG.Krimer The slow endogeneous rhythmic activity of pacemaker neurons for which gluconeogenesis provides the substrate appears to be controlled by the membrane-bound phosphofructokinase (PFK) and fructose 1,6-diphosphatase (FDPase). As shown in neuronal extracts PFK and FDPase are Under reciprocal control, with the PFK activators AMP and fructose-]j6-P 2 inhibiting the FDPase at higher concentrations, while the reverse is true for the FDPase activators citrate and 3-phosphoglycerate. Intra- and extracellular administration of these effectors of isolated neurons leads to marked changes in the regular spike frequency. For example, 1 - 2 m M fructose-1,6-P 2 increased the frequency from g to 4o imp/min whil~ 21~M citrate reduced the frequency from 35 to 9 imp/min. The decrease in the H/ ~C ratio of '[5-0 , U - ~ C ] fructose-6-P, together with an estimate of intraneuronal effector concentrations, indicates that in pacemaker neurons a PFK-FDPase-mediated snbstrate cycle operates in which ATP is split and protons are produced. When spike generation was blocked by tetrodotoxin oscillations of the membrane potential became uncovered which had the same time period as the original spike trains. Frequency and amplitude of these waves were increased by effectors of the PFK-FDPase system expected to accelerate the substrate cycle, while negative modifiers had the opposite effect. Fluctuations in the concentrations of H and ATP caused by the operation of the substrate cycle are postulated to affect the ion permeability of the membrane. Department of Physiology, University of Mainz, D 65 Mainz, Obere Zahlbacher Sir, Supported by the Deutsche Forsehungsgemeinschaft, Ch 25/].

R 84 167

EFFECTS OF ANTIPSYCHOTIC DRUGS ON DOPAMINE RECEPTORS IN APLYSIA NEURONS W.-D. Heiss~ J. Hoyer and G. Thalhammer Dopamine receptor blockade has been suggested as an important mechanism of action of antipsychotic drugs (S. Matthysse, Fedn. Proc. 32, 200, 197S). Receptors of putative synaptic transmitters may be'-studied directly in ganglion preparations of molluscs by intracellular recording of neuronal activity and by extracellular microelectrophoretic application of the test substances (H.M. Gerschenfeld, P~armac.Rev.53, I, 1973). The responses of identified neurons of Aplysia californica to microelectrophoretically applied dopamine~ acetylcholine and 5-hydroxytryptamine were investigated before and during perfusion with drug containing seawater. Haloperidol (50juM), fluphenazine (10 and 100 pM)~ thioridazine (100 ~M) decreased or blocked H- as well as D-responses of neurons elicited by dopamine application. Washing with drug-free seawater for 30 - 100 min reversed the effects of the neuroleptic drugs on the dopamine response in all neurons. In contrast to these observations responses to microelectrophoretic application of acetylcholine or 5-hydroxytryptamine were not impaired by the drugs. The non-antipsychotic phenothiazines mepazine (10 and 100 ~M) and promethazine (100 ~M) had no or only a slight depressing effect on the dopamine response. The results provide a direct neurophysiological evidence for the specific blocking effect of 3 antipsychotic drugs on dopamine receptors and agree with neurochemical~ pharmacological and indirect physiological observations. Institut ffir allgemeine und vergleichende Physiologie~ SchwarzspanlerstraBe 17~ 1090 Wien 168

BENZODIAZEPINE ACTION ON SYNAPTIC TRANSMISSION,ACTION rCTENTIAL AND IONIC CURRENTS IN APLYSIA NEURONS J.Hoyer, W.-D.Heiss and M.R.Klee ..... Diazepam (Valium) and flurazepam (Dalmane) are benzodiazepines with similar clinical and pharmacological effects but different ~ater solubility. Their influence on membrane properties and synaptic transmission was studied in ganglion cells of Aplysia californica. Because of its solubility most of the experiments were done with flurazepam. The synaptic transmission between interneurons and their follower cells showed a reduction of EPSP amplitude and also IPSP with higher concentrations. To test the direct effect of the drugs on the post-synaptic receptor, ACh was applied phoretically on different cells. Flurazepamblocked the D-responses while the H-responses were unaffected. At the same time the resting potential was reduced bY42 - IOmV and the uembrane resistance increased. Flu~azepam, 10 M, reduced the spike amplitude by 5-30% and 5xiO M by 15-55%. The duration of the spike was prolonged up to 4 times by the lower and up to 15 times by the higher concentration. This prolongation was represented by a plateau occuring during the falling phase of the spike and corresponds with data from voltage clamp experiments, mostly done in cell R-2: The maximum effect was a reduction of 60% in the inward and of 80% in the outward current. The observed changes of membrane properties may lead to an impaired propagetion of the action potential. These effects might explain why benzodiazepines supress the spreading of seizures. Allg. u. vergl. Physiol., Univ.Wien, A-IO90, Schwarzspanierstr. 17 MPI Brain Res.,Dept.Neurobiol.,D-6Frankfurt 71,Deutschordenstr. 46

R 85 169

REDUCTION OF EVOKED TRANSMITTER RELEASE AND FAILURE OF NERVE TERMINAL INVASION DURING SYNAPTIC DEPRESSION IN CRAYFISH H. Hart and D.O. Smith Junctional potentials evoked by repetitive stimulation of the motoneuron supplying the crayfish opener muscle were examined by intra- and extracellular recording techniques. As the period of stimulation became longer, an initial facilitation was observed and was found to result from an increase in the average number of quanta released (m) and in the average probability (p) of their release. Following this, depression was observed which resulted from a decrease in m and p as well as from failure of some impulses to invade all of the nerve terminals. This resulted from conduct i o n blocks at regions of axonal bifurcation where the safety factor for impulse propagation is low. The frequency of spontaneously released quanta remained unchanged although the average number of evoked quanta (m) decreased during depression. Evoked transmitter release may occur at release sites that differ in some way from those at which spontaneous release occurs. Physiologisches Institut der Technischen Universitat D 8 MOnchen 80, Ismaninger Strasse 19

MOnchen,

170

ASPARTATE: A COMPETITIVE AND OF EPSPs IN CRAYFISH

INHIBITOR OF GLUTAMATE J. Dudel

SYNAPTIC ACTION

At the crayfish neuromuscular ~unctlon glutamate postsynaptic currents (E-EPSCs) can be generated by iontophoretic application of (L)-glutamate through high-resistance (80-200 M~) micropipettes (Dudel, PflGgers Arch. 355, 329, 1975). In a bathing solution containing 10-100 mmol/l o ~ a - ( L ) - a s p a r t a t e the glutamate dose which produced a half-maximum g-EPSC was increased by a factor of 2 to I0, while the maximum E-EPSC generated by a saturation dose as well as the slope of the dose-response curve were not affected. EPSCs elicited by stimulation of the motor nerve fiber were also depressed by aspartate, but the effect on the EPSC was ~maller than that on the E-EPSC. By recording extracellularly at 2 C the quanta contained in the EPSPs could be determined directly. In Na-aspartare solution the quantum size was reduced, while the average number of quanta, m, released per stimulus and also the probability of release, p, were not altered. Even after prolonged applications, the effect of aspartate on the g-EPSC was immediately reversible; in contrast, the ampl~tude of the quantum EPSP recovered within up to 30 minutes. It appears that aspartate inhibits competitively the reaction of glutamate with the synaptic receptor with no appreciable effects on the nonsynaptic muscle fiber membrane or on transmitter release. The slow recovery of the~EPSP may indicate a temporary release of aspartate as a false transmitter. Physiologisches Institut der Technischen Universitat M~nchen, D 8 M~nchen 80, Ismaninger Strasse 19

R 86 171

TRANSNEURONAL PASSAGEOF PROTEINPRECURSORSAND INHIBITION OF TRANSFER AFTER DECOUPLINGOF ELECTROTONICSYNAPSES. A. Hermann and E. Rieske Intraneurona] iontophoretic injection of tritiated protein precursors combined with subsequent autoradiography is well suited for studying transneuronal molecular communication. The technique permits both intracellular recording of electrophysiological parameters of neurons and examination of transport processes. An excellent preparation for studying intra- and interneuronal material fluxes provides the morphologically and electrophysiologically well-examined segmented lateral giant axon (LGA) of the crayfish. The alternative use of two fixatives (formal and glutaraldehyde) allows the differentiation between radioactivity in soluble material and macromolecules. Formation of new postfixative channels by gluteraldehyde couldnot be substanti ated. From the site of injection into the axon the protein precursors were found to cross the nonrectifYing electrotonic synapses at the septa and the commissural junctions and to move by diffusion and/or retrograde axonal transport to the somata, where they are incorporated into macromolecules. No transcellular~ transfer could be shown to occur between LGA and other neurons or glia] cells. Exchange of precursors across the septa is interrupted after electrical decoupling of the synapses by low CI" or CaZ+, hlgh" pH or mechanical injury of the LGA. Therefore, the sites of electrotonic coupling may also be the sites of biogenic material transfer. Department of Neurophysiology, Max-Planck-lnstitute for Psychiatry, D-8000 Munich 40, ~raepelinstraBe 2 (6.F.R.) 172

CHANGESOF EXTRACELLULARPOTASSIUMCONCENTRATIONIN RELATIONTO ONSETOF SELFSUSTAINED AFTERDISCHARGES U. Heinemann and H.D. Lux According to the potassium accumulation hypothesis (Green, Phys.Rev.44, 501, 1964), an increase in extracellular potassium concentration (a~) above a critical value should initiate seizure activity. We have attempted to t~st this hypothesis using potassium sensitive electrodes. Although repetitive stimulation of the cortical surface or the nucleus ventroposterolateralis thalami produces selfsustained afterdischarges (SAD) when cortical aK is increased to values above 4.5 mM/l, the character and duration of SAD are not related to the amount of rise in a~. In addition, SAD thresholds do not follow aK levels during recovery. Following the stimulus-induced increase, a~ decays to values below baseline activity (2.8 to 3.4 mM). No SAD can be evoked i n i t i a l l y during the decay. However, SAD thresholds can be less than controls before the normal a~ is restored. SAD thresholds are not lowered also when av is increased by potas~'ium iontophoresis (4 to 10 mM). We tried also to al~er changes in aK by the antiepileptic drug diphenylhydantoin (DPH, 15 mg/kg B.W.). After DPH a~ could reach levels near 10 mM/l wi!thout evoking SAD. In addition, DPH decreased the maximum value of stimulus induced a~ increases and deepened and prolonged subsequent av undershoots. The resultS" suggest that K+ accumulation may play only a minob role in seizure initiation.

Department of Neurophysiology, Max-Planck-Insti tute for Psychiatry, D-8000 Munich 40 (G.F.R.), Kraepelinstra~ 2

R 87 173

EFFECTS OF NOREPINEPHRINE, DB-c-AMP AND THEOPHYLLINEON THE EXTRACELLULAR POTASSIUM ACTIVITY IN THE VISUAL CORTEXOF THE CAT. K. Zander, U. Heinemann and H.D. Lux Extrace] lular potassium acti vi ty (a~) was measured by potassium specifi c microelectrodes in Area 17-18. Baseline ~K ranged between 2.8 to 3.2 mM. Stimulus induced decrease in aNwas evoked by repetitive low frequency (4 to 8/sec) stimulation in the lateral geniculate body (CGL). Increase in av was evoked by cortical surface (CS) stimulation, high frequency CGL stimulation or potassium iontophoresis. Norepinephrine (NE), but not DB-c-AMP and theophylline, slightly reduced the baseline aN (maximum reduction 0.3 mM). DB-c-AMP, but not NE enhanced the stimulus induceB aN decrease by about 10%. DB-c-AMP and theophylline togetzer enhanced i t apprBximately 20%. Stimulus induced a~ increase was reduced by DB-c-AMP. The iontophoretically induced aK increase gas reduced and the decay to baseline aN accelerated by DB-c-AMP and NE. These effects ranged also between 10 to 20%. The observations are discussed in view of the possible role of NE and DB-c-AMP in inhibitory and active transport mechanisms.

Department of Neurophysiology, Max-Planck-Institute for Psychiatry, D-8000 Munich 40, Kraepelinstrasse 2 (G.F.R.) 174

REGIONAL C H A N G E S OF H +- A N D K+-ACTIVITIES IN C E N T R A L NERVOUS S TI~UC TURES DURING SENSI TIVE AC TIVA TION D. Heuser, G.L. Lenzi, N. Battistini,C. FiesChi It is well known, that concommittant to changes in the functional activity of the CNS regional increases of CBF and augmentation of oxidative metabolism occur. In o r d e r to obtain informations, whether the increased CBF and the activated metabolism a r e reflected in changes of H+, and K+-activities of the extracellular space in the central nervous tissue, we p e r f o r m e d the following experiments: In c u r a r i z e d cats under Fluothane anaesthesia, we stimulated afferent fibers of big d i a m e t e r s (B-fibers) by means of a stimulating electrode in a cutaneous n e r v e (Superfic. radial, nerve). Changes of extracelluiar H+and K+-activities were r e c o r d e d continuously with m i c r o e l e c t r o d e s on the s u r face of the exposed N. cuneatus and on the field of the cortical projection of the stimulated nerve. Though we always obtained good evoked potentials we only saw slight acid shifts on the s u r f a c e of the N. cuneatus. These shifts occured only, when Fluothane was turned off for s h o r t time o r if it was applied in v e r y low concentrations. We never saw shifts in the K+-activity on the N. cuneatus and never obtained changes of pH and K+ on the cortex. The observed pH-changes were related closely to the functional activity, bec a u s e they w e r e not present on the c o n t r a l a t e r a l nucleus cuneatus. The presented data will be discussed in r e s p e c t to the regulation of regional CBF. Institute of Physiology (I), Tuebingen, W . - G e r m a n y Clinica delle Malattie n e r v o s e e mentali dell' Universita, Siena, Italy

R 88 175 SOM~ E X P E R I M E N T A L RESULTS S U P P O R T I N G A N E W H Y P O T H E S I S A B O U T NA +C U R R E N T "ACTIVATION AND I N A C T I V A T I O N " IN M Y E L I N A T E D NERVES A. Tippe and H. M O l l e r - M o h n s s e n

U s i n g laser pulses (t=20 ns,~=347 nm) m o r p h o l o g i c a l lesions (~l~m diameter) w e r e p r o d u c e d in various regions of a Ranvier node in order to study the c o r r e l a t i o n b e t w e e n m o r p h o l o g i c a l structures and e l e c t r o p h y s i o l o g i c a l functions (H. M d l l e r - M o h n s s e n et al., Z . N a t u r f o r s c h . 3 0 c , 2 7 1 , 1 9 7 5 ) . The influence of these lesions on action potential, m e m b r a n e p o t e n t i a l and c u r r e n t - v o l t a g e c h a r a c t e r i stic was investigated. Lesions in the p a r a n o d a l region cause an i r r e v e r s i b l e b r e a k d o w n of action potential, whereas r e s t i n g potential and I - V - c h a r a c t e r i s t i c r e m a i n unchanged. E l e c t r o n m i c r o g r a p h s of this region show h i g h l y ordered structures w i t h junctions between the c o m p o u n d m e m b r a n e of the m y e l i n and the axon m e m b r a n e (R.B.Livingston et al., Brain Res.58,1,1973). U s i n g an e l e c t r o n probe x - r a y m i c r o a n a l y s e r a high Na c o n c e n t r a t i o n was found w i t h i n the m y e l i n structure p a r t i c u l a r l y close to a node (A.D~rge,R.Rieck A . T i p p e in progress). These e x p e r i m e n t a l facts t o g e t h e r w i t h the o b s e r v a t i o n of action p o t e n t i a l s g e n e r a t e d by a node bathed in a Na-free h y p o s m o t i c s o l u t i o n (containing only KCI) (A.Tippe,H.MOller-Mohnssen, N a t u r w i s s e n s c h a f t e n in press) support a new h y p o t h e sis about the N a - c u r r e n t "activation and inactivation" process. This h y p o t h e s i s assumes that Na is stored w i t h i n the p a r a n o d a l organ and r e l e a s e d in d e f i n i t e doses to the axon m e m b r a n e by a supert h r e s h o l d stimulus. W i t h i n this picture N a - i n a c t i v a t i o n is simply caused by d e p l e t i o n of Na ions due to the inward current. D e p a r t m e n t of P h y s i o l o g y

GSF

D - 8042

Neuherberg

Germany

176 I N T R A C E L L U L A R RECORDINGS F R O M THIN SLICES OF THE DORSAL LATERAL

GENICULATE BODY

(LGBd) OF THE G U I N E A PIG

R. S c h a u m b e r g

This t e c h n i q u e was s i m i l a r to that u s e d by Y a m a m o t o (Exp. Brain Res. 14, p.423-435, 1972), the t i s s u e - c h a m b e r was modified. The slices w e r e about 4 O O ~ thick and cut in the sagittal plane. G l a s s - m i c r o e l e c t r o d e s , filled w i t h 1,5 M p o t a s s i u m - c i t r a t e and h a v i n g r e s i s t a n c e up to 1OO MR, w e r e used for i n t r a c e l l u l a r re= cordings. One s t i m u l a t i n g - e l e c t r o d e , made of tungsten, was p l a c e d in the optic tract w h e r e it enters the nucleus, another in the nucleus itself. The r e s t i n g - p o t e n t i a l of p e n e t r a t e d cells was u s u a l l y about 30-70 mV, the s p i k e - a m p l i t u d e s ranged from 30-60 mY. The L G B d - n e u r o n e s could always be d i s c h a r g e d o r t h o d r o m i c a l l y and/or antidromically. The latency of the initial spike changed, d e p e n d i n g on the d i s t a n c e of the s t i m u l a t i n g electrodes. Stirm/lation of the optic tract p r o d u c e d a steep EPSP, w h i c h always reached threshold. S t i m u l a t i o n in the nucleus itself p r o d u c e d either an a n t i d r o m i c or an o r t h o d r o m i c spike-discharge. Some cells showed p r i m a r y inhibition, the amplitude of w h i c h i n c r e a s e d w i t h stimulusstrength. The decay of the IPSP was s u p e r p o s e d by slowly rising EPSP, w h i c h r e a c h e d threshold, if the stimulus i n t e n s i t y was in = creased. W i t h such a stimulus intensity, another steep rising EPSP w i t h s h o r t e r latency developed. Max-Planck-Institut Am FaBberg

f~r B i o p h y s i k a l i s c h e Chemie,

D-34 G6ttingen,

R 89 177

SIMULTANEOUS RECORDINGSOF SPONTANEOUSSYNAPTICEVENTSWITH TWO FOCAL ELECTRODES FROMTHE FROGNEUROMUSCULARJUNCTION. A. Wernig From morphological findings i t appears that there are discrete structures in the presynaptic terminal membrane at which transmitter release might occur (Couteaux, M.R. and Pecot-Dechavassine, M., C.r.hebd.S~anc.Acad.Sci.Paris, 271, 2346, 1970). Experiments have been performed to investigate whether q'uantal release in the frog neuromuscular junction happens at discrete points along the far stretched 'Endverzweigung' of the presynaptic axon. When spontaneous synaptic activity is recorded with a single extracellular electrode, no consistant frequency amplitude relation can be observed (del Castillo, J. and Katz, B., J.Physiol., 132, 630, 1956). Therefore, spontaneous synaptic activity was recorded with two extracellul ar gl ass micropipettes. Under visual control (normal optics, magnification 200) the electrodes were located a few microns apart, such that identical quantal events were monitored simultaneously. Signal amplitudes of the two electrodes were plotted against each other. Assuming exponential decrease of the signal with distance from the recording electrode, results from some experiments suggest that quantal events take place at discrete spots in the terminal region. In connection with the 'active zones' seen in the presynaptic nerve terminal (Couteaux et al., 1970), i t is likely that release occurs at these structures. Department of Neurophysio]ogy, Max-Planck-Institute for Psychiatry, D-8000 Munich 40, Kraepelinstrasse 2 (G.F.R.) 178

NOISE ANALYSIS OF A C E T Y L C H O L I N E INDUCED CURRENTS D E N E R V A T E D R A T ~K/SCLE FIBRES ~ B. Sakmann

IN NORMAL AND

Voltage clamp currents were recorded during iontophoretic application of acetylcholine to endplates of normal and extrasynaptic membrane of ~2-16 day denervated rat d i a p h r a g m fibres. Noise analysis (B. Katz and R. Miledi, J. Physiol. 224, 665, 1972) of drug induced current fluctuations by means of the a u t o c o r r e l a t i o n function has been made and the mean duration T and amplitude i of the elementary current pulse was calculated. At a temperature of 21-23~ and at holding potential of -7OmV the value of i found in normal fibres i (norm) =2,4 -0,07 pA (mean ~ S.E.; n= 6 ) was only slig~tlydifferent from the value found in denervated fibres i(den)=1,76 -0,1 pA(n~1). The values of ~ w e r e much longer in denervated fibres ~'Iden)= 3,81 O,14 msec; (n= 11) than in normal fibres ~-(norm)=O,96 !0,O4 msec; (n= 6 ). The longer duration of the acetylcholine induced elementary current pulse in denervated muscle membrane could account for the o b s e r v a t i o n that the d e g r e e of extrasynaptic acetylcholine sensitivity in denervated rat muscle fibres is as high as the endplate sensitivity of normal fibres although the density of receptors is lower in the extrasynaptic mem brane (H.C. Hartzell and D.M. Fambrough, J. Gen. Physiol. 60, 248, 1972). Abt. Neurobiologie, M a x - P l a n c k - I n s t i t u t D 34 G~ttingen, Am Fassberg

fur B i o p h y s i k a l i s c h e

Chemie,

R 90 179

TAURINE: POSTSYNAPTIC A C T I O N AND S E N S I T I V I T Y TO S T R Y C H N I N E ON SPINAL MOTONEURONS OF THE FROG. P . G r a f e ~ G . K r u m n i k l I N.Linder~ U . S o n n h o f During intracellular recordings from motoneurons of the isolated frog spinal c o r d , R i n g e r solution was t e m p o r a r i l y replaced b y solutions containing amino acids.Taurine,as well as GABA, glycine,a- and B-alanine caused effects,which are typical for postsynaptic inhibition: b l o c k a d e o f a n t i d r o m i c spike invasion, decrease of the amplitude of postsynaptic p o t e n t i a l s , i n c r e a s e of membrane conductance and a membrane p o l a r i z a t i o n corresponding to the direction of the IPSP.Taurine produced the strongest i n h i b i t o r y effects followed b y 8 - a l a n i n e , a - a l a n i n e , G A B A and g l y c i n e . S t r y c h n i n e , w h l c h influenced the postsynaptic potentials a n d caused rhythmic discharges of m o t o n e u r o n s , d i m i n i s h e d the effects of taurine,a- and S-alanine and glycine,without influencing the G A B A - a c t i o n . H o w e v e r , d i f f e r e n c e s i n the susceptib i l i t y to strychnine b e t w e e n taurine and the other ~mino acids were o b s e r v e d . L o w concentrations of strychnine (flO- M) only suppressed the action of taurine and not glycine,a- and B-alanine effects~After a p p l i c a t i o n of high strychnine concentrations (5xIO- M) glycine,a- and B-alanine regained their inhi~itory p o t e n c y when their c o n c e n t r a t i o n was increased to 2xI0- M, while the taurine action was still completely b l o c k e d . T h e s e results m a y be a hint for a possible function of taurine as a transmitter of a strychnine-sensitive postsynaptic inhibition in the spinal cord of the frog. I. P h y s i o l o g i s c h e s Institut, U n i v e r s i t ~ t Heidelberg, Im Neuenheimer F e l d 326 180 EFFECTS OF TYPE A B O T U L I N U M TOXIN ON SOME SYNAPTIO TRANSMISSIONS IN THE SPINAL CORD OF CATS~ B e n e c k e + ~ R o H a ~ e n a h + + p H o W i e ~ a n d +++ The question arises whether or not botulinum toxin exerts additional effects on the central nervous system, which could be masked by the pronounced peripheral effects~ In order to elucidate this problem the effects of botulinum toxin on the well defined central cholinergic synapse on Renshaw cells (RC), on the RC inhibition on Ia inhibitory interneurones (IaIN), and on the mutual inhibition of RC were investigated. Techniques of direct intraspinal injections, injections into the ventral root, and into the triceps surae muscle (local botulism) were used. The results obtained were as follows: Io Direct intraspinal injection causes a reduction of the early response of spinal RC. 2. Injections of botulinum toxin into the ventral root L 7 do not affect the cholinergic transmission on RC. 3o In the early phase of local botulism neither a change of RC activity nor a reduction of RC-induced inhibition on IaIN or other RC could be observed~ From these results it is concluded that b o t u l i n u m toxin influences central cholinergic transmission only in case of direct intraspinal injection~ If the toxin, however, accumulates in the spinal cord after the more physiological ascent in e f f e r e n t nerve fibres no effects on the investigated systems appear. It is suggested that in the latter case most of the toxin is especially concentrated in motoneurones than in other neuronal structures, + ++ +++

Physiologisches Institut der UniversitMt G~ttingen Neurologische Klinik der UniversitMt Hamburg Pharmakologisches Institut der UniversitMt GieBen

R 91 181

SYNAPTIC ORGANISATION

IN RAT SOMATOSENSORY

CORTEX.

J. Houchin

Rats were anaesthetised with urethane. Intracellular recordings were used to study spatial and temporal patterns of excitation and inhibition in cortical neurones following electrical stimulation of the contralateral forepaw. Procion Yellow dye was injected into some of the cells. The initial response was stable and localised (area diameter
THE EFFICIENCY OF DIFFERENT NEURONAL CODES: INFORMATION TRANSFER CALCULATIONS IN DIFFERENT NEURONAL SYSTEMS R. Eckhorn, O.-J. GrUsser, J. Kr~ller, K. Pellnitz and B. P~pel

Information theory calculations were performed whereby different codes were applied to the same neuronal impulse data obtained from four different neuronal systems (retina, lateral geniculate body, muscle spindles and DSCT-neurons of the cat) under various stimulus conditions. A code approximately matched to the system properties was chosen by taking a time-weighted average of the input. The weighting function was derived from the cross-correlation between input and output. Computations of the trans-info~mation T obtained with this weighted average code and the "frequency code" in comparison to those wi(~ the signal code" {i.e. without code restrictions) show the loss of T due to code restrictions. In all computations of the weighted average code, T was 90 to 99% of that of the signal code, i.e. nearly all information had already been transmitted solely by the linear part of the signal coupling. T of the "frequency code", however, approximated T of the "signal

code" less closely (5-gz%). The dependence of these differences upon the rate and s t a t i s t i c a l structure of the input impulse train as well as the importance of these findings for the application of information theory to neurophysiology are discussed. Supported by the Deutsche Forschungsgemeinschaft (Gr 161, P~ 115/

3).

Physiologisches I n s t i t u t der FU Berlin, O-1 Berlin 33, Arnimallee 22.

R 92 183

PROPERTIES OF SLOW POTENTIAL CHANGES IN EVOKED POTENTIALS P. Finkenzeller und W.D. Keidel Eigenschaften lanqsamer Potential~nderungen in evozierten Potentialen In Erwartung eines eine motorische Aktion befehlenden Reizes tritt in den frontalen EEG-Ableitungen eine negative Gleichspannungskca~oonente auf (CNV), die praktisch yon der Reizmodalit~t unabh'~ngiq ist. ~bhl auf Grund ihrer relativ groBen Amplitude yon teilweise mehr als 20/uV wurde eine weitere, zwar kleinere aber sehr stabile perstimulatorische Potential~nderung mit deutlich anderen Eigenschaften bisher nur wenig untersucht. Dazu wurde eine Reihe yon Experimenten mit kor~olexen akustischen und ootischen Reizen ausgeftthrt. Neben der einfachen Mittelun~ von 4 s lanqen EEG-Absdnnitten des Menschen und ECG-Abschnitten von implantierten Elektroden der Katze wurden Beziehungen zu zus~tzlich berechneten LeistunqssDektren und zur Phase zwischen Reiz und ~-Rhythmus des EEG hergestellt. Auf Grund ihrer groSen Stabilit~t, der unterschiedlichen tooooraohischen Verteilung und dem Zusammenhang mit den fz~Enen evozierten Potentialen darf die perstimulatorische DC-Komponente bei der Beurteilung yon evozierten Potentialen nicht vernachl~ssigt werden. Institut fox Physioiogie und Biokybernetik, Universit~t Erlanqen-Ntirnberw, Universit~tsstra.~e 17, D-852 Erl~n~en 184

EEG VIGILANCE IN REAL DRIVING SITUATIONS and H. Fruhstorfer

U. Pfas

J.H. Peter

Vigilance and attentiveness of train drivers is usually tested by devices which require certain motor responses. The continuous performance of this "secondary task" over years may, however, improve the ability of the driver to respond correctly in states of lowered vigilance during which his overall performance is reduced This problem has to be studied by comparing the performance of the secondary task with objective electrophysiological vigilance indicators. In a first step EEG, EOG and ECG were studied in healthy subjects when d r i v i n g a car during daytime or at night. The driving situation was also recorded by video camera. One experiment usually lasted 3 hours. The route consisted of 5o km highroad, loo km monotonous motorway and again 5o km highroad. Besides a visual examination, the EEG was evaluated by calculating power spectra and Hjorth parameter. The first results show that especially when driving on the motorway, short bursts of 12-15 Hz activity appear with increasing frequency of occurrence. At the same time, eye movements become slower and slow spontaneous shifts appear. The appearence of 12-15 Hz bursts is in good correlation to the subjective reports of phasic drowsiness. Supported by the Deutsche Forschungsgemeinschaft (SFB 122/B 2) Physiologisches

Institut D-355 Marburg/Lahn,

Deutschhausstr.

2

R 93 185 THEEFFECT.OF.FOREPERIOD REACTION TIME EXPERIMENTS ON THE EEG,G.Pfurtscheller Four EEGs of the central and occipital region of 8 healthy subjects under CNVconditions (Psychiat. Nervenkr. 20___66,309, 1967) were recorded and analysed. The CNV-conditions were provided e i t h e r by the stimulation-sequence click-tone-button or click-flashes-button. Control experiments (click-tone or click-flashes) were also effected. On each experiment 30 pairs of stimuli were presented, the inter-stimulus i n t e r v a l being 1.6 sec each. The average powers in the 8...13 Hz band (P~)(N=8) in 8 overlapped 1-sec-segments in the pre-, i n t e r - and p o s t - s t i mulus i n t e r v a l were calculated of a l l experiments. I t was found that on reaction time experiments in the inter-stimulus interval and shortly a f t e r a s i g n i f i c a n t decrease of P~ in the'central derivations can be observed. I t was on an average greater with flashes than with tones. In occipital derivations a small e r decrease of Pa could be .observed, which was more s i g n i f i c a n t with flashes, too. I t was found that the p r o b a b i l i t y for a short reaction time is greater,the greater the decrease of P~ in the inter-stimulus i n t e r v a l i s . I n s t i t u t e of Biomedical Engineering, Technical University of Graz, A-8olo Graz, Inffeldgasse 18 186 RE-TEST RELIABILITY OF VISUAL EVOKED RESPONSE (VER) WITH AND WITHOUT SIMULTANEOUS REACTION-TIME (BT) RECORDING. A. Taghavy In order to correlate parameters of reaction time (RT) and simultaneously recorded evoked pohentials (A.Taghavy, E. Hoh, EEG-EMG, 6, 45, 1975) it is necessary to check their reliability. In Io trained normal individuals VER to foveal visual stimuli of i/3 see. frequency were summated with a computer of average transient in two sessions with and without simultaneous reaction time recordings. I.) The configuration of the potentials starting 12o msec after the stimulus (N2-P3-N3) tended to remain stable within limits. 2.) Great inter-indivldual differences were noted. 3.) In most instances the intra-individual differences were slight. 4.) Intra-individual latencies were more stable than the corresponding amplitudes. 5.) The latency of P3 in first session was 165 t 17 msec whereas 169 • 13 msec in second session across individuals, the correlation coefficient being Rho= 0,89 P ~0,01. 6.) The simultaneous reaction time recording did not change the latency of P3 significantly, when compared to V E R w i t h o u t reaction time measurement. The correlation coefficient between 2 sessions was calculated to be Rho= 0,9~ P ~ O , 0 1 . The results will be compared with those of reaction t i m e / a n d concluded, that certain quality of evoked potentials may be a more stable characteristic of individuals. Universit~ts-Nervenklinik,

852 Erlangen, Schwabachanlage lo.

R 94 187 THE ROLE OF DENTATE AND INTERPOSITUS ~UCLEI IN SIMPLE REACTION TIME IN CEBUS MONKEYS J. Meyer-Lohmann~, J. Hore t t and V.B. Brooks ++ Does the cerebellum p a r t i c i p a t e in the i n i t i a t i o n of movement by influencing motor cortex discharge? Simple reaction time to a visual GO signal was i n v e s t i gated in 3 Cebus monkeys that were trained to make elbow flexions and extensions by moving a handle in a horizontal arc. Reaction time was defined as the time from the GO signal to onset of EMG in biceps or triceps and to movement onset as detected by a v e l o c i t y threshold. Mean reaction times were of the order of 200-250 msec from GO signal tooEMG onset and 250-300 msec grom GO signal to movement onset. Cooling to 7.5 C probe reference temperature through stereot a x i c a l l y implanted probes adjacent to e i t h e r the dentate or interpositus nucleus, increased mean reaction times by 50-100 msec as measured by onset of e i t h e r EMG or movement. Raster plots o f u n i t s recorded in motor cortex revealed that in general t h e i r normal r e l a t i o n to movement onset was preserved during cerebellar cooling. However cooling changed the overall discharge a c t i v i t y of some units while the discrete pattern of a c t i v i t y of others was l o s t . These results support the opinion that the cerebellum is involved in the i n i t i a t i o n Qf movement through i t s influence on motor cortex. +Physiologisches I n s t i t u t der Universit~t, Lehrstuhl I I , 3400 G~tingen, Humboldtallee 7 ++Department of Physiology, University of Western Ontario, LondonN6A 3K7, Ontario, Canada 188 INTRACORTiCAL PROPAGATION OF TONIC SEIZURE PATTERNS P.Rappelsberger, 0.Prohaska, H.Petsche and R.Vollmer During epileptic seizures, periods of regular and apparently synchronous activity around 10 Hz usually occur. This study was aimed at defining the degree of "synchronism" in different cortical layers. It was carried out on curarized rabbits. Seizures were produced by epicortical application of g-Penic~llin. Recordings were made from horizontally arranged pairs of microelec~rodes inserted into the cortex through an Ag-AgCI ring electrode for surface recording. The degree of intra- and transcortical synchronism was computed by a method described previously (P.Rappelsberger et al., Quantification of the EEG II, Vevey 1975), based on a comparison of the signs of the first differential coefficients of two recordings. The degree of synchronism between cortical surface and depth depends on two parameters: (I) distance from surface, (2) time elapsed since the beginning of the seizure. The time-shift between intra- and epicortical recordings decreases during tonic seizures to attain a final value characteristic for each lamina. These findings demonstrate that, originating in the deep pyramidal layer, a continuous corticopetal propagation with increasing speed takes place (from 3.3 to 13 cm/sec). This is in agreement with the previously stated hypothesis of an active antidromic conduction in the apical dendrites during seizures. Institute of Neurophysiology of the University of Vienna, and Brain Research Institute of the Austrian Academy of Sciences, W~hringerstraSe 17, A 1090 Wien

R 95 189 THE E S T A B L I S H M E N T OF P A T T E R N E D N E U R A L C O N N E C T I O N S A C C O R D I N G TO A THEORY OF S E L F - O R G A N I S A T I O N D.J. W i l l s h a w and C. v o n d e r M a l s b u r ~ The m e c h a n i s m s by w h i c h ordered c o n n e c t i o n s are set up b e t w e e n pairs of neural structures are not yet known. C u r r e n t theories stress the importance of the s p e c i f i c i t y of i n d i v i d u a l c e l l s . Each pre- and p o s t - s y n a p t i c cell is assumed to be p r o v i d e d w i t h a un~/ue label, and d u r i n g d e v e l o p m e n t each pair of m a t c h i n g cells is able to couple together. - The fact that such m a p p l n g s are contlnuous, that two cells w h i c h are neighbours in the p r e - s y n a p t i c array c o n n e c t to n e i g h b o u r i n g cells in the p o s t - s y n a p t i c array, means that the k n o w l e d g e that a p a r t i c u l a r pair of cells has made contact is a v a i l a b l e to guide their pre- and p o s t - s y n a p t i c n e i g h b o u r s to their own destinations. We discuss how continuous m a p p i n g s can be set up on a t h e o r y of self o r g a n i s a t i o n based on this idea. We show h o w our general p r i n c i p l e s can be embodied in an e l e c t r i c a l m o d e l in w h i c h g e o m e t r i c a l d i s t a n c e is coded in terms of c o r r e l a t e d electrical a c t i v i t y b e t w e e n n e i g h b o u r i n g cells and where use is m a d e of the concepts of excitation, i n h i b i t i o n and m o d i f i a b l e synapses. We d e s c r i b e c o m p u t e r s i m u l a t i o n experiments d e m o n s t r a t i n g that our ~odel d i s p l a y s "systems matching" (Gaze and Keating, Nature 237, 375, 1972) which, a c c o r d i n g to r e c e n t experiments, is a p r o p e r t y p o s s e s s e d by the r e t i n o - t e c t a l system in amphibia and fishes. D e p a r t m e n t of Neurobiology, M a x - P l a n c k - I n s t i t u t e for B i o p h y s i c a l Chemistry, D 34 G~ttingen, Am Fassberg

190 EEG AND TPV~NSCENDENTALMEDITATION

W, Krahneand B. Taneli

Spectral analysis and conventional EEG were investigated in 10 healthy subjec~ experienced in Transcendental Meditation (TM), as thought by Maharishi Mahesh Yogi. Recordings were made with a 12-channel-EEG-recorder and stored on magnetic tape. Each session lasted 45-50 min (10 min before TM, 25-30 min TM, 10 min after TM). A push button permitted the subjects to indicate the state of meditation whenever they started thinking their "mantra". Results: During TM, high amplitude alpha and theta periods were seen in all ~regions, especially frontal. In the later stages of TM, these periods were of longer duration. This synchronized activity was often interrupted by desynchronized periods, consisting largely of beta waves which showed a maximum increase around 20 c/sec. A correlation existed between the termination of thesedesynchronized periods and the button-push signalling the onset of "mantra". Subjective (post-session questionair~ and objective (EEGrecording~ f i n d i n g s revealed a relationship between the amount of thinking during TM and the recorded EEG:if the number of bouts of thinking was described as low,there was an increase in the EEG integral in the frontal regions and a decrease in the occipittal regions. When thenumber of bouts was described as high, however there was a decrease in the integral in both regions. In each case, the changes were maximal 15-20 min after the beginning of TM and decreased towards the end. During TM, the alpha waves generally showed a decrease in frequency and an increase in amplitude. The EEG changes were different from those seen in states of wakefulness, drowsiness and sleep, but showed some similarities to other forms of relaxation. For related investigations, see Bauquet, Electroenceph. clin. Neurophysiol. 1973, 35 : 143-151. Dept. of Physiology I I , Univ. of G~ttingen, D-3400 G~ttingen, Humboldtallee 7

R 96

191 EEG POWER SPECTRA AND AUDITORY EVOKED POTENTIALS IN TRANSCENDENTAL MEDITATION (TM) G. Kobal, A. Wandhoefer and K.-H. Plattig We reported in 1973 a shortening of latencies for auditory sl0w evoked potentials in subjects before and during performance of TM compared with a control group in a "normal" and in a dozing state (A. Wandhoefer and K.-H. Plattig, PflGgers Arch., Supp. 343 R 79, 1975). - In the experiments described here 6 intensities were applied as auditory stimuli (1000 Hz tone, 600 ms duration) to the above subjects (15 practitioners of TM and 15 students for control) with same conditions as before. Amplitudes and areas of the averaged potentials were computed on a PDP 11/40 and compared by variance analysis. Power spectra of the underlying EEGs in periods of 3,8 s were gained and also averaged. - Results: Latencies of peaks of evoked potentials were shorter in the TMgroup (p
K. Nier and H. Hensel

By application of graded unidimensional micro-vibration to placoid scales of Selachian skin the transformation characteristics of mechanosensitive receptor afferents were investigated in Scyliorhinus canicula. Suprathreshold sinusoidal stimulation throughout the frequency band of 0.05 to 500 Hz led to synchronized impulse patterns recorded from single- and multi-fibre preparations of the external mandibular branches of the nervi V and VII. As for the signal parameters, input intensity is represented by the intraperiodical impulse rate (and additional by the number of fibres activated in multiple units). Input frequency is transmitted by the afferent burst rate. The amplitude frequency response of the 1/1- as well as the upper synchronization levels show a significant dependence on the input frequency with a broad threshold minimum enclosed by approx. ~2o dB /decade slopes in the lower frequency range. Following the synchronization criteria for Bode plot ~evaluation the gain and phase parameters were averaged inside thestimulus period each. With high frequency response the phase data reveal an increasing phase lag according to a medium dead-time of circa 14 msec. Especially the dynamic behaviour can be characterized by a quasi-linear second-order D(T,Tt)-component within the biologically relevant amplitude and frequency matrix. Inst.of Physiology, Univ.of Marburg, D355 Marburg, Deutschhausstr.2

R 97 193 DORSAL HORN CELL A C T I V I T Y TO THERMAL S T I M U L A T I O N SCROTAL SKIN. T. Neya a n d Fr.-K. Fierau

OF RAT'S

Previous recordings from t h e r m o s e n s i t i v e afferents of the puden~al nerve in the rat d e m o n s t r a t e d a variety of different reactions to temperature changes of the receptive area in the scrota~ skin (J~Neurophysiol. 38,601,1975). Hellon and Misra (J.Physiol. 232, 375,1973) found a similar pattern of responses in the dorsal horn of Ehe rat by thermal stimulation of the scrotal skin. To further reveal spinal p r o c e s s i n g of peripheral temperature signals we studied in a n e s t h e t i z e d rats the dorsal horn cell responses to temper a t u r e changes of the scrotal skin with e x t r a c e l l u l a r recordings by means of glass m i c r o p i p e t t e s filled with a blue dye. Fifty -four single units responded to peripheral temperature changes~ 36 increasing their activity with w a r m i n g and 9 increasing their activity with cooling of the scrotal skin while the rest showed more complex responses. As a striking feature most of the w a r m units only r e s p o n d e d to peripheral temperature chan~es above a certain temperature which was in the range of 37-40 C in more than 70% of the neurones. Al'though not s y s t e m a t i c a l l y tested at temperatures above 42~ often the temperature responses appeared to have on-off characteristics. Similar reactions appeared in the neurones r e s p o n d i n g to cooling, in many cases only showing a temp eratu r e response b e l o w 38~ Some also had a threshold at lower temperatures w h i c h limited the temperature responses to a range of 3-5UC. In 9 experiments thermal stimulation of the scrotal skin also e f f a c t e d systemic blood pressure, but e x c l u s i v e l y above a threshold of about 37.5~ MPI

fur P h v s i o l o g i s c h e

und K l i n l s c h e

Forschung,

D-635

Bad N a u h e i m

194 EFFECTS OF OUABAIN AND C A L C I U M ON TEMPERATURE RESPONSES OF COLD RECEPTORS O F THE CAT TONGUE. Fr.-K. Pi:erau and R.D. ~urster. It was recently suggested from experiments on the rat scrotal skin that an e l e c t r o g e n i c sodium pump participates in the r e c e p tor m e c h a n i s m of p e r i p h e r a l cold receptors (Brain Res. 73, 156, 1974). In an attempt to further test this hypothesis, the effect of ouahain injection into the lingual artery (0..02-0.04 mg/kg) on the response of single cold sensitive afferents of the cat tongue was investigated. In all fibers ouabain increased static activity but in some p r e f e r e n t i a l l y in the temperature range above 28~ In some cold receptors the dynamic response to a cooling step of about 3~ was changed twofold: firstly, b el o w 24~ the discharge transi e n t l y increased with the temperature drop but then was mom e n t a r i l y inhibited; secondl~: a w a r m i n g step from 18~ (the coldest temperature used) to 21 C elicited a transient increase in discharge. In some cold fibers the b u r s t i ng pattern, w h i c h was the common feature in the tongue receptors we investigated, tended to r e c r u i t m o r e impulses in a burst. - Since calcium is also reported to effect the response of temperature receptors we tested the influence of different calcium concentrations on cold receptors in the tongue by means of constant intraarterial infusions. In all c a s e s p f i r s t the static activity disappeared, but dependent on the calcium concentration, the transient response to a cooling step remained. The results support the notion that a metabolic control of cold receptor activity exists. An i n t e r a c t i o n of this m e c h a n i s m with the effect of calcium on cold receptors has yet to be revealed. MPI

f~r P h y s i o l o g i s c h e

u~d Klinische

Forschung,

D-635

Bad N a u h e i m

R 98 195

PERIPHERAL COMPONENTS IN SHORT TERM HABITUATION. and H. Hensel

K. Sch~fer

In our experiments apecific cold receptors in the nasal reglon of cats were examined by recording afferent impulses from single units dissected from the infraorbital nerve. The receptors were stimulied with a water circulated thermode with a contact area of 10 mm diameter. The thermode was first perfused with water at 3ooC for 5 minutes and then with water at 4 ~ C for 60 aeconds. After a further 60 seconds at 30 ~ C the cold stimulus was repeated. In most receptors six cold stimuli were applied. In all cold fibres the height of the overshoot decreased with the second cold stimulus, but this value did not vary with successive cold stimuli. Five fibres could be held long enough to apply seven cold stimuli and they showed an average maximal dynamic frequency of 115 imp/sec (SD + 3,5) after the first cold stimulus, and 97 (• 3), 95 (• 3), 96 (+_-2), 97 (• 3), 96 (2 2,5) and 97 (• 2,5) imp/sec, respectively, in successive cold stimuli. After the initial dynamic discharge most fibres were silent during the cold stimulation while the 300 C interval was not long enough to allow the receptors to reach the initial static level at that temperature. Institute of Physiology, University of Marburg, D-3550 Marburg, DeutschhausstraBe 2 Supported by the Deutsche Forschungsgemeinschaft. 196 CUTANEOUS WARM FIBER A C T I V I T Y I N ~TL~AN SUBJECTS

~. Konietzny

and H. Hensel In conscious human subjects afferent impulses from specific warm fibers were examined by recording with microelectrodes inserted percutaneously in the superficial branch of the radial nerve. Quantitative thermal stimulation was achieved by a device operating on the Peltier principle. The stimulator had a contact area of 12 mm in diameter and allowed continuous adjustment of temperatures at any po~int in the range from 5 ~ to 45 ~ C. Linear temperature changes could be controlled between rates of greater than 2~ to less than 0.03~ A total of 3 units responded to moderate warming of the skin. Their receptive fields were situated on t h e d o r s a l surface of the index finger and the dorso-medial side of the thumb. Two of these units h a d c o n d u c t i o n velocities Of 0.5 and 0.75 m/sec, respectively. When the skin temperature was kept constant a single warm fiber showed a steady discharge increasing w i t h r i s i n g skin temperature. The average static maximum was 11 imp/sec at 45~ Warming the skin with linear temperature changes with a rate of 0.8~ starting from an adapting temperature of 35~ caused an overshoot in frequency, cooling caused a transient inhibition of the discharge, while tactile stimulation within the receptive field area of the warm unit was ineffective. The results support the assumption that in man the sensory quality of warm is due to the activity of a specific receptor population sensitive to warming. Physiologisches Institut, D-355 Marburg/Lahn, Deutschhausstr. 2 Supported by the Deutsche Forschungsgemeinschaft

R 99 197

A SIMPLE DEVICE FOR TESTING THERMOSENSIBILITY IN PATIENTS W. G. Schmidt,

U. Lindblom,

and H. Fruhstorfer

In clinical practice there is no simple, quick, and reliable method to examine the patient's thermal Sensibility. For this purpose a thermostimulator was designed w i t N which cold, warm and heat pain thresholds can be measured by applying pure thermal stimuli without tactile components. The stimulator consists of a set of Peltier elements which can be cooled or warmed by a constant current source. The direction of the temperature change can be selected by a switch. Similar as in a B6k&sy Audiometer the subject changes the switch position as soon as he perceives the stimulator getting warm or cold. The continuous recording of the stimulater zempera~ure gives a reliable estimate of the patient's thermal sensibility. It is a function of thresholds, thermal reaction times and adaptation processes. In c l i n i c a l s t u d i e s we found that different types of neurological and metabolic deseases may be clearly differentiated from normal subjects on the basis of thermal sensibility. The method has also been used in determining the loss of thermal sensibility during regional anesthesia, thus indicating the beginning af analgesia. Supported by the Deutsche

Forschungsgemeinschaft

Institut fur Physiologie,

D-355 Marburg/Lahn,

Karolinska 198 RECEPTIVE

Sjukhuset,

(Fr 265/2)

Deutschhausstr.2

S-I04 01 Stockholm

FIELD ORGANIZATION

JECTION AREA OF THE CAT

IN THE THALAMO-CORTICAL

C. Hellweg, W.Schultz

WHISKER PRO-

and O.D.Creutzfeldt

Cortical cells and thalamo-cortical fibers were recorded intraand subcortically in nembutalized and immobilized cats. The receptive fields of 76 units were determined by systematically stimulating the whiskers and the skin on the contralateral side of the cat's face. The aim Was to get information about the degree of functional convergence onto single cortical cells by comparing the receptive fields of thalamic fibers and cortical cells. It was found for units receiving exclusively whisker input that tonically firing thalamo-cortical fibers tended to have sharply focused receptive fields, mostly confined to Qne or two single vibrissae. The more phasically firing fibers frequently showed unspecific receptive fields. In a proportion of cortical cells (about 30%) the excitatory input as determined by intracellular recordings was also restricted to one or two whiskers. In the remaining 70% however, larger receptive fields were found and the stimulation of more than two whiskers could be effective. In addition, most cortical cells received inhibition from larger areas, sometimes including the whole whisker field. From these findings we conclude, that predominantly one, but to a lesser extent additional thalamo-cortical fibers often in a graded fashion can excite a single cortical cell, and that inhibition is converging from a wider area. Max-Planck-Institut Neurobiologie, D 3 4

fur Biophysikalische Chemie, G~ttingen, Am FaBberg

Abteilung

R 100 199 P A R A V A S C U L A R PAIN RECEPTORS~ A L G E S I C S U B S T A N C E S AND P R O S T A G L A N D I N S . F. Lembeck~ H. Juan and H. PoppeP Injections (i. a. ) of algesic substances into the isolated perfused r a b b i t e a r connected to the body by its n e r v e only e l i c i t s a dose-dependent r e f l e x f a l l in blood p r e s s u r e by s ti m u l a t i o n of paPavasculaP pain PeceptoPs. O r d e r of a c t i v i t y : bradYkinin >> ACh >> ATP~ histamine~ 5-HT~ KCI. Inactive: physalaeminI eledoisin~ adenosine~ a d r e n a l i n , angiotensin, oxytocin and PGE 1. Infusion of PGE1 (50 ng/ml) into the eaP~ howeveP~ enhanced the effect of alge sic substances ( b r a d y k i n i n >>ACh)2 w h e r e a s i n h i b i t i o n of P G - s y n t h e t a se by indomethacin inhibited t h e i r effect. PGF20{ led to a r e d u c t i o n of the effect of b r a d y k i n i n but not of ACh. The i n t e r a c t i o n between PGE 1 and PGF2(x is assumed to be competitive. The PGE I - r e l e a s e induced by injection of bPadykinin (threshold dose O. 1 ng) into the isolated pePfused r a b b i t e a r was measured by R I A and bioassay. BPadykinin-induced PGE1-Pelease disappeaPed under infusion of indomethacin. It is concluded that the Pelease of PGE 1 e x e r t s a f a c i l i t a t i n g Pole on the paPavasculaP pain PeceptoPs when stimulated by endogenous op exogenous bradykinin. Department of P h a r m a c o l o g y , U n i v e r s i t y of Graz~ A - 8 0 1 0 Graz~Univ. PI. 4

2OO DEVELOPMENT OF NOCICEPTORS IN REGENERATING CUTANEOUS NERVES OF THE CAT. H. Dickhaus~ M. Zimmermann~ and Y. Zotterman. In 10 cats the planta~ nerves which innervate the hind foot were crushed over a length of 5 mm at a distance of 20 to 40 mm from the area of innerva~ion. Conduction was interrupted by this procedure in all types of nerve fibres. Between I and 92 days after the nerve crush, single unit recording was performed to investigate the receptor characteristics of regenerating nonmyelinated (C) fibres. Results: 1) R e g e n e ~ C - f i b r e s were not excitable by adequate skin stimuli prior to 28 days after crush. From 40 days after crush about 16% of C-fibres could be excited by radiant heat. This corresponds to the proportion of "C-heat-receptors" in control animals. (Beck, P.W., Handwerker, H.O., Zimmermann, M. 1974). 2) The distribution of ~hermal thresholds to stimuli of 10 sec duration ranged from 36 C skin temperature ~n the regenerated C-fibres. Thus they were shifted b~ about 3 C to lower thresholds compared with control experiments. 3) The relationship between number of impulses discharged per 10 sec~thermal stimulus was measured quantitatively in 12 regenerated C-fibres. The intensity function of this population was steeper than in normal nerves and started at a threshold of 36~ 4) Some of the regenerating C-fibres were spontaneously active. These results are discussed in relation to hyperpathia in man. Supported by the Deutsche Forschungsgemeinschaft. II. Physiologisches Institut, 69 Heidelberg, Neuenheimer Feld 326, Germany

RI~ 201 A C T I V I T Y OF PONTINE NUCLEI CELLS E V O K E D BY V I S U A L A N D ELECTRICAL STIMULATION W.Fries and K.Albus Single unit activity and field potentials w e r e r e c o r d e d extrac e l l u l a r l y w i t h t u n g s t e n m i c r o e l e c t r o d e s in the pontine nuclei(PN) of a n e s t h e t i z e d and i m m o b i l i s e d cats. The PN w e r e reached through the c e r e b e l l u m h o l d i n g the animal in the u p r i g h t position. Stimulating electrodes w e r e p l a c e d c o n t r a l a t e r a l l y in the b r a c h i u m pontis (BP) and i p s i l a t e r a l l y in the s u p e r i o r colliculus (SC), the p e d u n c u l i cerebri (PC) and in four different p o s i t i o n in the visual cortex (VC); the correct p o s i t i o n i n g was v e r i f i e d h i s t o l o g i c a l l y . In the experiment, neurons w e r e i d e n t i f i e d as PN cells w h e n they could be driven o r t h o d r o m i c a l l y by both VC and PC s t i m u l a t i o n and a n t i d r o m i c a l l y f r o m BP. Latencies to VC s t i m u l a t i o n ranged b e t w e e n 2 and 12 msec. A n t i d r o m i c latencies from BP ranged b e t w e e n 0.5 and 0.9 msec. A n u m b e r of c.ells in the more caudal part of the pons could be d r i v e n b o t h by VC and SC s t i m u l a t i o n (latencies to SC s t i m u l a t i o n b e t w e e n 1.5 and 5 msec). F o l l o w i n g e x c i t a t i o n e v o k e d by VC and SC s t i m u l a t i o n in some cells an i n h i b i t o r y pause lasting 20 - 200 m s e c was seen~ Surprisingly, only few cells driven by e l e c t r i c a l s t i m u l a t i o n r e s p o n d e d to visual stimuli. These units had large r e c e p t i v e fields (about 30~ 30 ~ ) in w h i c h a small, fast m o v i n g light p o i n t ~cted as an optimal stimulus. They w e r e relatively u n s p e c i f i c for o r i e n t a t i o n of contrast and d i r e c t i o n of movement. Besides their relay function in the c e r e b r o - c e r e b e l l a r loop, PN s e e m also to have an integrative function. W. Fries, M a x - P l a n c k - l n s t i t u t fHr B i o p h y s i k a l i s c h e Chemie, D-34 GSttingen, A m F a B b e r g 202

THE SPECTRAL PROPERTIES OF CLASS 1 , 2 , 3 AND 4 NEURONS OF THE FROG-!S OPTIC TECTUM U. GrUsser-Cornehls and R.McD. Saunders The spectral properties of class 1 , 2 , 3 and 4 neurons of the optic rectum o f the frog (Rana esculenta) were i n v e s t i g a t e d using equal energy s t i m u l a t i o n at various wavelengths between 400 nm and 600 nm. In these i n v e s t i g a t i o n s moving as well as s t a t i o n a r y stimuli were a p p l i e d . When determining the discharge r a t e of the on and off-response of class-3-neurons with s t a t i o n a r y chromatic s t i m u l i , only one "opponent colour" neuron could be found among 13 c l a s s 3-neurons. The off-response of t h i s neuron showed maximal spectral s e n s i t i v i t y to blue and the on-response to red. Experiments with moving black spots on a chromatic background c l e a r l y showed t h a t the discharge pattern of class i , 2 and 3-neurons depends on the colour of the background. 2 subgroups have so f a r been found among class-Z-neurons: one group showed maximal spectral s e n s i t i v i t y at 500 nm, another at 450 nm and a second maximum at 580 nm. D i f f e r ent velocities of the moving spot had no influence on the general feature of the neurons' spectral s e n s i t i v i t y . The exponent of the velocity function, however, was dependent on the spectral proper-

t i e s of the background. Supported by the Deutsche Forschungsgemeinschaft (Gr 2 7 6 / 7 ) . Physiologisches I n s t i t u t der Freien U n i v e r s i t ~ t B e r l i n , D lO00 B e r l i n 33, Arnimallee Z2.

R102 203

RESPONSES OF FROG TECTAL CELLS TO MOVING AND STATIONARY VISUAL STIMULI A. George and U. GrUsser-Cornehls

By means of microelectrodes ~e action potentials of single cells were recorded in the optic tectum of frogs (Rana esculenta). The responses to stationary and moving visual stimuli were investigated. 7 d i f f e r e n t major classes of visually activated tectal cells were found. Out of these 7 classes, class TI and T5 were investigated more intensively, Both classes have r e l a t i v e ly small receptive f i e l d s (20.40~ diameter). In contrast to T5neurons, the receptive f i e l d s of T1"neurons were located in the binocular visual f i e l d . T1-neurons were binocularly or monocularly activated. The velocity function of part of these neurons could be des- I cribed by a power function up to SO~ ~ (R-k.v ~ impulses.sec ). The exponentKwas between 0.3 and 1.3. In other neurons a maximal neuronal response occurred when the v e l o c i t i e s of the stimulus pattern was below 10~ "I . Investigations with stimulus patterns of varying sizes showed that this maximum partly depended on the size of the stimulus pattern. In part of the neurons the maximum of the area function was achieved at stimulus patterns below the receptive f i e l d size~ Measurements with stimulus patterns of varying shades of grey showed a less strong dependency of the neuronal response on the contrast. Directional s e l e c t i v i t y was observed in some neurons.Possible correlations between neurophysiological and behavioaral findings are discussed. Physiol. Inst. d. FU Berlin,D-1 Berlin 33, Arnimallee 22. 204 S Y N A P T I C D E L A Y , E X C I T A T O R Y C O N V E R G E N C E AND T E M P O R A L S U M MATION OF CLASS I AND CLASS II C E L L S , AND A P O S S I B L E A D D I T I O N A L C E L L T Y P E IN T H E L A T E R A L G E N I C U L A T E N U C L E U S U. Th. E y s e l intracellular recordings from different cells in the LGN of cats during electrical stimulation of the optic tract yielded the following results: (a) The synaptie transmission time from the pre-potential to the onset of the EPSPs was on the average 0.41 msee for class-l-cells and 0. 67 msec for class-If-cells. (b) Excitatory convergence, of up to 7 retinal afferent axons on one LGN-cell was shown with two different methods. (c) Temporal summation of up to 50% of the maximal PSP amplitude oeeured in class-I- and class-II-EPSPs at stimulus frequencies above 100Hz. The same was true for the fast group-I-IPSPs, While the slower group-II-IPSPs displayed comparable temporal summation at frequencies below 50 Hz. This is good evidence for the existence of an effective postsynaptic inhibition in the LGN of the cat, (d) In Ii of 97 cells no action potentials cou.ld be elicited by any method. These cells showed long stimulus-response latencies (I. 5-2.5 msec), slow EPSPtime-courses (average duration 17 msee), and on the average less negative resting potentials. Only in this cell-group convergence of EPSPs with distinctly different latencies was found. The possible morphological correlate to such LGN-neurons processing visual information only with slow potentials could be the unmyelinated, intraiaminar cells of the Golgi-2nd-type. Supported by the Deutsche Forschungsgemeinschaft Physiologisches Institut der FU Berlin, 1 Berlin

(Ey 8). 33, Arnirnallee

22.

R103 2q5 !r~TIGATIONS CORTEX OF CAT

WITH DOUBLE LINES ON SIMPLE CELLS OF THE VISUAL H.C.Nothdurft

The spatial resolving power of simple cells in the cat's visual cortex has been measured by optical stimulation with parallel light b~rs of 6 min. width, which had different spacings. The line pairs were moved across the receptive field, and each pair was taken as resolved if the cell-response was inflected between the lines by at least 10%. About 3o simple cells and for comparison Io fibers from the lateral geniculate nucleus (LGN) could be evaluated. In general terms the findings are the following: 1. T h e b e s t simple cells could resolve line distances of 16.5' (center t o center distance). The range of the resolving power of simple cells is shifted to greater line distances compared with the LGN-fibers. Furthermore the correlation between optimal resolving power of a cell and the width of its excitatory receptive field was much weaker than that in LGN-cells. 2. The response-characteristics of LGN-fibers are nearly linear, that means in the extracellular record the response to a double line corresponds to an additive superposition of two responses to single lines. In, contrast, the response-characteristics of most recorded simple cells were strongly nonlinear. Some of the observed nonlinearities, which cannot be understood with simple receptive field concepts, can be explained by a model which is based on a~ intracortical network. MPI ftir biophysikalische

Chemie, D 34

G6ttingen-Nikolausberg

206 RECEPTIVE FIELD ORGANIZATION OF SIMPLE AND COMPLEX CELLS IN AREA 18 OF THE CAT. G.A. 0 r b a n and M. C a l l e n s .

A previous study (G.A. Orban et al., Brain Res.9Q'205-210, 1975) suggested that as well simple cells as complex cells are found in area 18 of the cat. In order to test this hypothesis the different tests described by P.O. Bishop et al.(J.Physiol.219, 625-687, 1971; 231,31-60, 1973) for investigation of the receptive field orEani~a-tion of simple cells in area 17, were applied to area 18 neurons with peripheral projections. In the first test neurons are stimulated with moving (velocities 5 to 800 deg.sec-1) single edges and slits or dark bars of different widths. In the second test inhibitory and facilitatory regions of the receptive field are disclosed by the modulation of an artificial background discharge produced by a conditioning slit moving asynchronously with the testing slit. Both tests revealed that a class of area 18 neurons have exactly the same RF organization as the area 17 simple cells of which the main features in the optimal direction of motion are inhibitory flanks in addition to central discharge and subliminal excitatory centers. Complex cells were also tested with moving edges and slits. These neurons lack inhibitory flanks. Their discharge regions are larger than the discharge centers of simple cells. It seems therefore that in addition to the level of spontaneous activity, the way of responding to gratings ~and random patterns, the presence of inhibitory flanks and the diameter of discharge regions are other criteria for distinguishing between simple and complex cells. Laboratorium voor Neuro- en Psychofysiologie, siteit te Leuven, 6 Dekenstraat. 3000 Leuven,

Katholieke Belgium.

Univer-

R104 207

CO~OR SELECTIVITY OF NEURONS IN AREA 18 OF MONKEY VISUAL CORTEX. P. Gou~as* and J. KrGger The foveal projection of area 18 of paralysed Rhesus monkeys anesthetized with N20 was examined for neuronal color responses. Color selective cells are known to exist in area 17, the sole target zone of the primate lateral geniculate nucleus. Area 17 projects to at least four anatomically identifiable zones in prestriate cortex, and the problem whether color signals reach all or only certain of these higher visual areas is not yet solved. We measured the spectral responses of cells to moving stimuli comprising a total of 113 penetrations and 176 cells or cell groups in Io animals. Neurons responding to only a narrow band of the spectrum were found in 6 % of the penetrations. In these regions color contrast seemed to be a particularly effective stimulus. The vast majority of cells responded to all parts of the spectrum and usually better to yellow than to other colors. The efficacy of yellow was g r e a t e r w i t h small thsm with large stimuli suggesting some underlying color opponency. The action spectrum of these broad-band cells varied sigmificantly from cell to cell. In the same animal this variation was much greater among cells in different penetrations than among cells in the same penetration implying regional differences in color selectivity. We conclude that color information reaches area 18. Neurologische Universit~tsklinik mit Abt. ~t~r Neurophysiologie, 78 ~ e i b u r g i. Br. Hansastr. 9. * Awardee of the Humboldt Foundation, Bonn-Bad-Godesberg, FRG 2O8 TWO CLASSES OCULOMOTOR

OF EYE NUCLEI

POSITION OF THE

CODED MONKEYS'

NEURONS IN THE R, Eckmiller

The existence of various activity patterns of eye position coded motoneurons d u r i n g s a c c a d e s (V. Hennj B. Cohenj B r a i n R e s . ~ 561, 1972) i n v i t e s a d e t a i l e d a n a l y s i s of s e v e r a l d y n a m i c p a r a m e t e r s . S i n g l e u n i t s in the r e g i o n s of the I I I . , IV. and VI. n u c l e i w e r e r e c o r d e d t o g e t h e r with EOG' s for h o r i z o n t a l and v e r t i c a l eye p o s i t i o n s i n a l e r t m a c a q u e s . R e s u l t s : 1) Eye p o s i t i o n coded n e u r o n s c a n c l e a r l y b e s e p a r a t e d into two m a i n c l a s s e s ( e a r l y p e a k ( E P ) and l a t e peak(LP)) a c c o r d i n g to t h e i r a c t i v i t y p a t t e r n s d u r i n g s a c c a d e s i n the o n d i r e c t i o n . In c o n t r a s t to E P n e u r o n s which exhibit an i m p u l s e r a t e ( m ) peak at the v e r y b e g i n n i n g of each s a c c a d i c b u r s t , L P n e u r o n s t y p i c a l l y r e a c h t h e i r m a x i m u m IR well a f t e r half the s a c c a d i c t i m e and d e c r e a s e to the new p o s i t i o n coded IR with a t i m e c o n s t a n t of about 50 m s e c . 2) T h e m a x i m u m IR of E P n e u r o n s shows a b e t t e r c o r r e l a t i o n with s a c c a d e v e l o c i t y t h a n the diff e r e n c e b e t w e e n m a x i m u m and i n i t i a l IR while the o p p o s i t e is v a l i d for L P n e u r o n s . 3) T h e r e l a t i o n s h i p b e t w e e n d y n a m i c index(A. C r o w e , P. B. C. M a t t h e w s , J. P h y s i o l . ! 7 4 , 1 0 9 , 1964) and s a c c a d e v e l o c i t y shows s u b g r o u p s of data which s u p p o r t s the h y p o t h e s i s of a f u s i m o t o r a c t i v i t y i n f l u e n c e . 4) T h e d y n a m i c p a t t e r n s of L P n e u r o n s d u r i n g s a c c a d e s have s e v e r a l f e a t u r e s s i m i l a r to t h o s e of p r i m a r y s t r e t c h r e c e p t o r s d u r i n g r a m p - l i k e s t r e t c h e s . It is a s s u m e d that E P and L P n e u r o n s have d i f f e r e n t f u n c t i o n s i n the s y s t e m r a t h e r t h a n to be s i m p l y r e f l e c t i n g i n d i v i d u a l d i f f e r e n c e s i n m o t o n e u r o n e s . *) S u p p o r t e d by the D e u t s c h e F o r s c h u n g s g e m e i n s c h a f t D e p a r t m e n t of P h y s i o l o g y - A n a t o m y , U n i v e r s i t y of C a l i f o r n i a at B e r k e l e y and I n s t i t u t e of P h y s i o l o g y , F r e e U n i v e r s i t y , D 1000 B e r l i n 33, A r n i m a l l e e 92

R 105

209 VARIOUS

CLASSES

OF

UNITS

IN THE

GOLDFISH DURING EYE MOVEMENTS

MIDBRAIN

TECTUM

OF

THE

ALERT

M, Maekeben

The role of the fish midbrain rectum in the control of eye movements (EMs) has not yet been clarified, although it is implied by its rich supply with retinal afferent fibers. The responses of these and of tectal cells were recorded by means of tungsten microelectrodes from the tecta of m o r e than 80 alert goldfishes during spontaneous and optokinetiely elicited EMs. Their horizontal component was measured using an infrared light reflexion method. The afferents showed activity patterns corresponding to the features described by Jacobson et al. (Quart. J. Exp. Physiol. 49.199, 1964) and Wartzok et al. (J. Neur o p h y s i o l . ~ 588, 1973) for the p a r a l y z e d p r e p a r a t i o n . In c o m p a r i s o n , many t e c t a l neurons showed m o r e s l u g g i s h r e s p o n s e s to v i s u a l s t i m u l i , which, if s t a t i o n a r y , m o s t f r e q u e n t l y e l i c i t e d s u s t a i n e d ON- a n d / o r O F F - r e s p o n s e s . Stimulus m o v e m e n t s o m e t i m e s added d i r e c t i o n a l s e l e c t i v i t y . A few c e l l s w e r e a c t i v a t e d by moving v i s u a l s t i m u l i , but e i t h e r not at a l l or much l e s s by a c t i v e EMs, which could be explained by an i n h i b i t o r y input f r o m the " e f f e r e n c e copy" neurons d e s c r i b e d by Johnstone et al. (J. Exp. Biol. 54. 403, 1971). Some c e l l s did not r e s p o n d to v i s u a l s t i m u l i at all. D i s c h a r g e b e f o r e EMs, as in the monkey sup. colliculus(Wurtz et a l . , J. N e u r o p h y s i o l . 35. 575, 1972), was n e v e r o b s e r v e d . C e l l s s p e c i f i c a l l y coding r e t i n a l i m a g e v e l o c i t y , which could be c o r r e l a t e d with the slow phase of optokinetic n y s t a g m u s , w e r e n e v e r r e c o r d e d f r o m . The r o l e of the m i d b r a i n t e c t u m in the c o n t r o l of EMs is d i s c u s s e d in the light of the p r e s e n t findings. I n s t i t u t e of P h y s i o l o g y , F r e e U n i v e r s i t y , D 1000 B e r l i n 33, A r n i m a l l e e 22 210 VESTIBUL0-0CULAR INFLUENCES IN MAN DURING CONSTANT 0PTOKINETIC STIMULATION J.H.J. Allum, J. Dichgaus, and E. Koenig The interaction of optokinetic and vestibular stimuli in man during consta~at optokinetic stimulation was studied, oVeloQity trapezoids (acceleration and deceleration 3,6~9 or 12 /sec ~ for Io sec, constant velocity for ~o secs) were used to test vestibuloocular influences in # subjects. Simultaneously, a black and white vertically striped drum was ~otated around the subject at constant velocity (3o,6o~9o or 12o /sec with respect to the body). 0culomotor responses to body rotation in the dark (VN) and to exclusive surround motion (0KN) s e r v e d a s controls. In response to b o d y velocity changes the following modifications of nystagmus were obtained : I. Slow phase vel@city of nystagmus could b e suppressed with directionally contradictory inputs in # subjects and even reversed in 3 subjects. 2. With d i r e c t i o n a ~ ly confirming inputs slow phase velocity wa~ enhanced and could exceed the 0KN stimulus velocity by 5 to 2o /sec. 3. The modifications were dependent on both optokinetic and vestibular stimuli : with the same body acceleration~ greater modification was obtained for larger optokinetic speeds. 4. With the data the relative contribution of vestibulo-ocular and optokinetic control systems to nystagmus could be quantified. Department of Neurophysiologyq University of Freiburg, burg i. Br.~ Hansastr. 9, West Germany

D 78 Frei-

R 106 211 A F T E R E F F E C T S OF L O N G T E R M O P T O K I N E T I C AND V E S T I B U L A R S T I M U L A T I O N IN TURTLES R. Kohlhaas and R. yon B a u m ~ a r t e n Three groups of small turtles (Pseudemys scripta elegans)wer~ stimula-" ted inside stripe drums in the following way: The animals were restraint by thin n y l o n t h r e a d s so that they could move freely in an d out of the w a t e r but were p r e v e n t e d from rotating in any d i r e c t i o ~ In group one the c o n t a i n e r with the turtles was still, but the stripe drum rotated. In group two the stripe drum was still, but the container with the turtles rotated. In group 3 the container and the stripe drum rotated in the same d i r e c t i o n at the same speed. During the first day most turtles d i s p l a y e d head nystagmus and tried to turn against the d i r e c t i o n in w h i c h the container rotated or into the d i r e c t i o n of the stripe movement. After a s t i m u l a t i o n period of I-4 weeks the turtles were tested for a f t e r e f f e c t s by setting them free inside a large wading pool in the dark. The swimming movements of the turtles were recorded by p h o t g g r a p h y using a strob o s k o p i c light source. The turtles of group one did not display any significant aftereffects. The turtles of group 2 showed circling into the d i r e c t i o n of original r o t a t i o n and thus against the direction of relative original stripe movement. Group 3 showed a s i m ~ a r a f t e r e f f e c t by r o t a t i o n of the turtles into the d i r e c t i o n of the original rotation. It is c o n c l u d e d that I.) v e s t i b u l a r s t i m u l a t i o n caused stronger a f t e r e f f e c t s in the turtles then o p t l k i n e t i c stimulation, 2.) that for turtles, unlike man, angular v e l o c i t y represents a stimulus and that h a b i t u a t i o n to this stimulus occurs by the intracentral c o m p e n s a t i n g impulses. D e p a r t m e n t of Physiology, U n i v e r s i t y Obere Z a h l b a c h e r Strasse 67, Germany

of Mainz,

D-65

Mainz,

212 C O N V E R G E N C E OF O P T O K I N E T I C AND V E S T I B U L A R SIGNALS IN U N R E S T R A I N T FISH WITHIN A R O T A T I N G STRIPE D R U M R.J. yon Baumgarten, R. Kohlhaas, H. Vogel and W. Ohl

Young guppies (Lebistes reticulatus) of ].5 c m length were filmed inside a vertical rotating stripe drum. The fish swam h o r i z o n t a l l y in circles, trying to follow the stripes. The swimming speed depended on the distance of the fish from the axis of the cylinder. When the stripe drum was arranged in a h o r i z o n t a l position, the fish did not show any c i r c l i n g or looping. O b v i o u s l y they were prevented of doing so by the function of the otolithic system. When the stripes were d e s c e n d i n g in front of the fish, the longitudinal axis of the fish was tilted downward; when the stripes were ascending, the l o n g i t u d i n a l axis of the fish was tilted upward. Fish, which were lined up with the axis of the =ylinder, were rolled into the d i r e c t i o n of the stripe movement. It is concluded that the tilted and rolled p o s i t i o n of the fish i~ the ro t a t i n g stripe drum was caused by a c o n v e r g e n c e of o p t o k i n e tic and v e s t i b u l a r impulses in the brain. Since with the h o r i z o n tal stripe drum the otolithie function of fish can be tested, it was pr o p o s e d to use this method to m e a s u r e p o s s i b l e changes of otolltic s e n s i t i v i t y of the fish returning from the fish experiment in the A p o l l o - S o y u s Spaceflight. D e p a r t m e n t of Physiology, U n i v e r s i t y of Mainz, Obere Z a h l b a c h e r Strass~e 67, Germany.

D-65,

Mainz,

R 107 213 THE INFLUENCE OF THE MOVEMENT OF THE RETINAL PICTURE ON THE HUMAN EEG V. Relman and N.D. Keidel Einflu~

der retinalen

Bildverschiebung

a u f d e s m e n s c h l i c h e EEG

Aus f r ~ h e r e n U n t e r s u c h u n g e n U b e r A u g e n b e w e g u n g e n e r g a b s i c h ' u . a e eine h o h e K o r r e l a t i o n z w i s c h e n EEG und A u g e n b e w e g u n g e n b e i n i e d e r e n F r e q u e n z e n . D i e s e r Zusammenhmng w u r d e e r k l H r t d u t c h L a m b d a w e l l e n , d . h . d u r c h evozierte Potentiale d e r d u r c h d i e Augenbewegung b e d i n g t e n r e t i n a l e n B i l d v e r s c h i e b u n g . Zur g e n a u e r e n K 1 H r u n g d i e s e s Z u s a m B e n h a n g e s warden evozierte gemittelte Poten~iale bei verschiedener optiecher Reizgeb~qg gemessen: Einmal bei fixiertem Auge und bewegtem Relzmuster, dann bel willkUrllch bewegtem Auge und feststehendem Reizmuster, ferner bel yon au~en induzlerter Augenbewegung und feststehendem ReIzmuster. Die Frequenz der Bewegun9 wlrd zwischen I Hz und 10 Hz variiert. Die am Occiput gemessenen evozier%en Potentlale werden bel Bewegung der Augen noch yon der Gleichspannungsschwankun 9 des Augendlpols Uberlegert. Es zeigen sich UnCerschiede in der Form der evozlerten Potentlale bel den verschiedenen Reizgebungen. Ferner erglbt slch ein Einflu~ beider Anteile des evozierten Fotentlals auf des ungemittel~e EEG im Berelch zwischen I Hz und IO Hz f~r Amplituden der willk~rlichen und unwillk~rllchen Augenbewegumgen.

Instltut fur P h y s i o l o g l e und B i o k y b e r n e t i k d e r UnlversitKt E r i a n g e n N ~ r n b e r g , D 8520 E r l a n g e n , U n i v e r s i t ~ t s s t r a ~ e 17 214

ON THE DAMAGE OF GANGLION SPIRALE AND CORTI'S ORGAN AFTER NOISE AND TONE STIMULATION

W. Seiller and W. Firbas

Guinea pigs were stimulated for 25 days by a white noise of 100 - 115 dB. The decrease in the number of nerve cells in the spiral ganglion was measured.

A maximum decrease of 18% was

observed in the second turn of the cochlea. For exact frequency localisation tone stimulation is necessary.

Two groups of

albino rats were treted for 2 and 4 hours respectivly by a pure tone of 2,5 kHz and 100 dB. We found no reduction in acetylcholinesterase-activity

in Corti's organ. Three groups

of albino rats were stimulated by the same tone for 4, 10 hours respectivly.

6 and

The AChE-activity in the cytoplasm of

the spiral ganglion decreased with high significancy.

The results

are discussed and compared to findings of other autors. Institut f~r medizinische Ehysik & I. anatomisches Institut der Universit~t,

A I090 Wien, W~hringerstra6e

13

R 108

215 MEASUREMENT

OF SOUND T R A N S M I S S I O N

EXPERIMENT

U. Hoppe,

Objectivation

of Mach's

was accomplished ted in March of

DISTURBANCE

P. Pauschinger sound-drain

by an electronic

BASING ON WEBER'S

and M. Schiebe theory

in Weber's

experiment

set up which we first presen-

1975 at the spring-congress

of the German Society

Physiology.

In c o l l a b o r a t i o n with the Clinic of O t o r h i n o l a r y n g o l o g y

in TG-

bingen the device

field

could be applied in clinical research

to prove its efficiency.

Results

comparation with clinical

are given and discussed

investigations.

device can be used routinely w i t h o u t major problems any considerable

stress for the patients.

that m e a s u r e m e n t

of existing

mission

apparatus

asymmetries

Evidende

and without is given

of homan sound trans-

is routinly possible.

D e p a r t m e n t Physiologie,

Universit~t

Ulm, D 79 Ulm, Postfach

216 DEMONSTRATION: TELEMETRICAL IVIICROELECTRODE AUDITORY PATHWAY IN FREE-MOVING CATS (A Film in Color with Sound Track) W.D. Keidel, K. Burian

in

It is shown that the

P. Finkenzeller,

A. WandhGfer,

S. Kallert,

STUDY

OF

4066.

THE

A. F6rstel

The film begins with the surgical preparation of a cat, shows the implanting process, the conditions of recording and concludes With s o m e of the results obtained by this method. Duration: ca. 25 Minutes Institut fiir Physiologie und Biokybernetik der Universit~it Erlangen-Nfirnberg~ D-8520 Erlangen, Universit~tsstra~e 17

R 109 217 R E G E N E R A T I O N I N T H E D A R K OF R H O D O P S I N IN P E R F U S E D RETINA K. Azuma, M. A z u m a and W. S i c k e l

VERTEBRATE

In i s o l a t e d retina, m a n y i n v e s t i g a t o r s f o u n d no s i g n i f i c a n t a m o u n t of r h o d o p s i n b e i n g r e g e n e r a t e d a f t e r b l e a c h i n g . H o w e v e r , r e c e n t e x t r a c t i o n studies have s h o w n that the b l e a c h e d r h o d o p s i n r e g e n e r a t e d in the d a r k (C. C r a m e r and W. Sickel, P f l Q g e r s Arch. 35~, R 110, 1 9 7 5 ) . ~ h i s s t u d y was c a r r i e d out in o r d e r to f o l l o w b l e a c h i n g and r e g e h e r a t i o n in the f u n c t i o n a l l y p r e s e r v e d r e t i n a and d e t e r m i n e the k i n e t i c s of the p r o c e s s e s . B l e a c h i n g / r e g e n e r a t i o n cycles were p e r f o r m e d in i s o l a t e d frog r e t i n a s p e r f u s e d w i t h s t a n d a r d m e d i u m (pH 7.7; temp. 18-20 ~ C). T r a n s m i t t a n c e was m o n i t o r e d c o n t i n u o u s l y at wavelengths 380,420, 500 and 600 nm,resp. T e m p o r a l s u m m a t i o n of the b l e a c h i n g e f f e c t f o l l o w e d an I x T rel a t i o n s h i p up to 15 min, w h i c h i n d i c a t e s little regeneration d u r i n g the e x p o s u r e to the b l e a c h i n g light. F o l l o w i n g b l e a c h e s of not more than 5 % of the r h o d e p s i n i n i t i a l l y present, complete r e g e n e r a t i o n of the v i s u a l p i g m e n t c o u l d be obtained. The y i e l d of r e g e n e r a t i o n was the same a f t e r b l e a c h i n g w i t h c u t - o f f f i l t e r s of 445 and 550 nm,resp. H a l f - t i m e of r e g e n e r a t i o n was about 7 min. The r e g e n e r a t e d p r o d u c t p r o d u c e d e l e c t r i c a l light r e s p o n s e s c o m p a r a b l e to the p a r e n t pigment. R e g e n e r a t i o n was i m p a i r e d in o x y g e n lack and on e x p o s u r e to light b l e a c h i n g more than 10 % of the r h o d o p s i n . I n s t i t u t fGr n o r m a l e und p a t h o l o g i s c h e P h y s i o l o g i e U n i v e r s i t ~ t , D-5 KGln 41, R o b e r t - K o c h - S t r . 39

der

218 A M O L E C U L A R M O D E L OF T H E I N F L U E N C E OF Ca 2+ ON T H E M E T A R H O D O P S I N I-II T R A N S I T I O N H . M . E m r i c h * and R. R e i c h

The

effect

transition using meta

of C a 2+ on k i n e t i c s was

flash-photometry. I with

-ions I-II

have

increasing

dynamic

description

-interaction c lamp

with

the p o l a r o u t e r (closed)

thus

leading

results

part

the

to the

equilibrium

are

I-II

model

entrance

reduction

w i t h M g 2+.

As a

and C a 2+ to

groups)

at

action

of p r o t o n s t o

observed

C a 2+

Ca 2+ is a s s u m e d

and thus

clamping

located

to s t a b i l i z e

Dept.Physiol.D-8000

Munich

the

of Ca 2+ is assu-

thecatalytic

centre,

of p r o t o n - c a t a l y s i s .

Max-Volmer-lnst.Phys.Chem.Mol.Biol.Techn.Univ.Berlin-West. * O n leave:

to

of the m e t a

of the p r o t o n -

(or d i p o l e

of the m o l e c u l e The

is s h i f t e d

we communicate a thermo-

transition.

charges

I-II

solutions

Furthermore,

obtained

results

of a m o l e c u l a r

fixed

of the m e t a

on protor~catalysis

of these

Ml-conformation.

to i n h i b i t

effect

the m e t a

two n e g a t i v e

I-II

Ca 2+ - c o n c e n t r a t i o n .

Similar

interpretation

and e q u i l i b r i u m

in r h o d o p s i n - d i g i t o n i n

The m e t a

an i n h i b i t o r y

transition.

possible

med

investigated

2, P e t t e n k o f e r s t r . 1 2

R 110 219 RECEPTOR RETINA

C O N T R I B U T I O N TO S E C O N D O R D E R N E U R O N M. Azuma, K. A z u m a and W. S i c k e l

ACTIVITY

IN F R O G

F o u r types of light r e c e p t o r s have b e e n c h a r a c t e r i z e d by t h e i r p e a k a b s o r p t i o n : c o n e s (575), a c c e s s o r y cones (502), r e d rods (502), and g r e e n rods (432) ( L i e b m a n and Entine, V i s i o n Res., 1968). The p r e s e n t i n v e s t i g a t i o n is an a t t e m p t to i d e n t i f y t h e m f r o m t h e i r c o n t r i b u t i o n to the e l e c t r i c a l light r e s p o n s e s . S p e c t r a l E R G r e s p o n s e c h a r a c t e r i s t i c s were i H ~ e B t S g a t e d ~n p e r f u s e d f r o g r e t i n a s u n d e r v a r i e d c o n d i t i o n s of a d a p t a t i o n , bwave a m p l i t u d e s and e - w a v e delays w e r e e v a l u a t e d . 5 mM/l a s p a r tare w a s used in some e x p e r i m e n t s to i s o l a t e P I I I - r e c e p t o r a c t i v i t y . S e l e c t i v e s p e c t r a l a d a p t a t i o n f a v o r e d 5 7 5 - c o n e and g r e e n rod a c t i v i t y , reap.. W i t h w h i t e b a c k g r o u n d s of i n t e r m e d i ate i n t e n s i t y s t r o n g e r b - w a v e r e s p o n s e s were m e d i a t e d by g r e e n rods and 5 7 5 - c o n e s than by 5 0 2 - r e r red rodswere h i g h l y a c t i v a t e d to p r o d u c e b o t h a- and e - w a v e s . In dark a d a p t a t i o n r h o d o p s i n rods are the o n l y f u n c t i o n i n g r e c e p t o r s , w h e r e a s in l i g h t a d a p t a t i o n g r e e n rods and 5 7 5 - c o n e s t r i g g e r b - w a v e a c t i v i t y . H o w e v e r rods are not s i l e n t in light a d a p t a t i o n . T h e i r o n - c o n t r i b u t i o n is e x c l u d e d b y the f a s t e r c o n e / g r e e n rod signals, n e v e r t h e l e s s they give rise to off rea c t i o n s w i t h a delay. The f u n c t i o n a l s i g n i f i c a n c e of a c c e s s o r y cones remaines obscure. ! n s t i t u t f~r n o r m a l e und p a t h o l o g i s c h e P h y s i o l o g i c U n i v e r s i t ~ t , D-5 K a l n 41, R o b e r t - K o c h - ~ t r . 39

der

220 ERG OF THE ISOLATED GUINEA PIG RETINA AS INFLUENCED BY ANIONS H. Hellauer and R. Winkler The prepared scotopic retina divided a chamber into 2 separate compartments and had a bilateral supply with Ringer's solution of original or substituted salt contents. An alternating (16 min change) use of the solutions (31 ~ C, 0.15 M, no admixtures, 4 ml/min of total flow) revealed amplitude changes of retinal b-wave response to light flashes (20/rain). But a continuity of solution supply served to define the survival time (min) of this response. If the substitute (of NaCI) was Nal the survival time extended from a medium of 51.00 (min) + 9.00 (standard deviation) to 68.18 + 3.71 (p<0.05) and the b-wave amplified in atl 3 relevant tests. For NaBr, e smaller and unsignificant extension (to 56.25 + 7.18) and an absence of b-wave increase was found. The substitute NaF drastically shortened both, survival time (to 15.00 +__0.57) and b-wave amplitude. All guinea pigs used in these tests did not exceed 1 year of age. The survival time of older ones extended to 80.00 + 7.60 for NaCI, and the figures for Nal, NaBr and NaF amounted to 90.00 + 0.58, 67.00 + 14.36 and 48.00 + 6.01 respectively. The substitutes NalO3, NaSCN and NaCIO4 reduced the survival time and amplified the b-wave. A stop of solution run caused reduction of b-wave amplitude within 15 rain from 43.3 to 14.4 % (flash continued)and from 37.3 to 13.1% (flash eliminated). Physiologische Abteilung, Paracelsus-lnstitut, Parkstral~e 10, A-4540 Bad Hall, Ober6sterreich

R 111 221

DOES THE ELECTRORETINOGRAM OF P I COMPONENT ? L. Wfindsch

CANIDAE

CONTAIN

THE

The ERG of the C a n i d a e fox (Cants [Vulpes] vulpes) and dog (Canis lupus f a m i l i a r i s ) is c h a r a c t e r i z e d by a v e r y pronounced b--wave caused by the negative P H I component. A c-wave (and the P I component which causes it) does not s e e m to be present ( W i i n d s c h , 1966, 1971). In o r d e r to check whether P I is actually absent or only m a s k e d by P I I I component, quinine was used. Small doses of quinine which do not influence the initial p a r t s of the ERG extinguish the c-wave r e v e r s i b l y in the cat ( H o r n mer, Ulrich and W i i n d s c h , 1968). Similar or somewhat higher dosages used in the dog do not alter the course of the b -wave. T h e r e f o r e it can be a s s u m e d that no masking occurs, T h e s e r e s u l t s suggest that the P I component ac.%ually is not p r e s e n t in the ERG of C a n i d a e . Institut fiir Aligemeine und Vergleichende Physiologie, UniversiC/t Wien, A - 1090 W i e n , SchwarzspanierstraBe 17 222 ON THE C E L L U L A R ORIGIN OF THE b-WAVE IN THE ERG

G. Rager

The c e l l u l a r origin of the b-wave in the ERG is still disputed. P o s s i b l e sources of the b-wave are either the b i p o l a r cells or the M ~ l l e r cells. We found with the electron m i c r o s c o p e that a r o u n d the time w h e n a b-wave can first be r e c o r d e d in the chick retina (late 18th day Of incubation) the M U l l e r cell c y t o p l a s m becomes more and more electron dense and the n u m b e r of o r g a n e l l e ~ e s p e c i a l l y microtubules, is very much increased. E l e c t r o p h y s i o logically we found that signal t r a n s m i s s i o n to the optic tectum after light s t i m u l a t i o n is already possible at a time w h e n only a pure r e c e p t o r p o t e n t i a l can be recorded in the ERG (late 17th and early 18th day of incubation). Since signal t r a n s m i s s i o n from p h o t o r e c e p t o r s to the optic tectum is not p o s s i b l e w i t h o u t bipolar cells, we conclude that the b-wave does not o r i g i n a t e in b i p o l a r cells, but more likely in MUller cells.

M a x - P l a n c k - I n s t i t u t f0r b i o p h y s i k a l i s c h e Chemie, A b t e i l u n g N e u r o b i o l o g i e , D 34 G6ttingen, Am F a B b e r g

R 112 223

CYCLIC VARIATIONS IN THE SPECTRAL SENSITIVITY OF GOLDFISH ELECTRORETINOGRAM. L. Wiindsch and W. HGfler

The dorsal light response ("Licht-Riicken-Reaktion") has long been known in several species. Using different coloured light stimuli, L a n g (1972) found that the dorsal light response in the guppy (Lepistes reticulatus) showed cyclic variations in its spectral sensitivity which proved to be coincident with the lunar phases. We recorded the ERG in the goldfish (Carassius auratus) to orange (583 nm) and blue (432 nm) light throughout several lunar cycles. The b-wave amplitude ratio for the two wavelengths changed statistically significantly at new moon and full moon, respectively. Therefore, it can be assumed that a retinal component is at least partially responsible for the lunation coincident dorsal light response. Institut fiir Allgemeine und Vergleichende Physiologie, Universi~t Wien, A - 1090 W i e n , Schwarzspanierstraf~,e 17 224 EFFECT OF DIPHENYLHYDANTOIN (DPH) ON CAT RETINAL GANGLION CELL ACTIVITY Dirk Stange and Johannes Vesper Recordings with tungsten microelectrodes from 186 single optic tract fibers revealed a marked effect of DPH (initial dose 15 rng/kg, followed by continuous infusion of 0. 3 rng/kg/h) on the maintained neuronal activity and the response to ~iffuse light flashes of 0.7 Hz and ii. 7 Hz (maximal luminance: 20 000 cd/m ~, 50 ~sec duration, background luminance 30 cd/m2). Under the influence of DPH off-center neurons showed an increased maintained activity up to 800 % while on-center neurons displayed only a transient decrease to 0 after injection and recovered Go normal values within 10 rain. The described effects are not related to blood pressure changes. During light stimulation the mean impulse rate of off-center neurons increased significantly in both of the applied stimulus frequencies, but more with 0.7 Hz flash-frequency. In contrast the decrease in the mean impulse rate of on-center neurons after DPH application was more distinct at a flash frequency of ii. 7 Hz. A decrease in after-discharges was seen in poststimulus-time histograms. Possible Supported

rnechanisrns

of DPH-action

by the Deutsche

Physiologisches

at the retinal network

Forschungsgemeinscnaft

Institut der FU

Berlin,

D 1 Berlin

are discussed.

(Ve_58). 33, Arnimallee

22.

Rl13 225

ISCHAEMIA EFFECTS~ON~RECEPTIVEFIEEB PROPERTIES OF RETINAL GANGLION CELLS DURING ACUTE INCREASED INTRAOCULAR'PRESSURE F. Grehn and D, Stange Microelectrode recordings from single optic t r a c t l f i b e r s were obtained. The intra~c~lar pressure (lOP)was raised in steps up to the mean a r t e r i a l blood pressure. The maintained neuronal a c t i v i t y was already influenced considerably at a moderate lOPincrease, whereas the center response to modulated l i g h t stimu l i could be e l i c i t e d up to IOP~levels near the d i a s t o l i c blood pressure. There was no gross change in the diameter of the receptive f i e l d center during pressure-induced ischaemia. The inh i b i t o r y e f f e c t of the receptive f i e l d periphery was e l i c i t a b l e as long as a neuronat response was obtained by s t i m u l i p r o j e c t ed to the r e c e p t i v e f i e l d c e n t e r ; A t critical perfusion pressures the f l i c k e r response was r e s t r i c t e d to a tow s t i m u l u s f r e quency range (2-10 Hz). The c r i t i c a l f l i c k e r fusion frequency decreased as the IOP increased above 40 mm Hg. A l l e f f e c t s observed in o n - ~ d o f f - c e n t e r neurons were r e v e r s i b l e i f the IOP was reduced to a normal l e v e l . Supported by the Deutsche Forschungsgemeinschaft (Gr 161 and GP

S3B/Z).

Physiologisches Institut allee 22.

der FU B e r l i n ,

D-1 B e r l i n 33, Arnim-

226

ALCOHOL WITHDRAWAL 'IN THE CAT: MICROELECTRODE RECORDINGS FROM THE OPTIC TRACT Dirk Stange

To study the effects of chronic ethanol exposure on the nervous system single fibre recordings were performed in the optic tract during alcohol withdrawal. The experimental animals were injected daily with 3 g ethanol/kg hodyweight intravenously for Io to 14 days. In encephale-isolepreparation then the properties of retinal receptive fields were studied 12 to 36 hours after blood alcohol level returned to O. The high maintained activity of on-center-neurons showed typically double and triple discharges. Many on-center-neurons followed the modulation of the stimulating light with modulation of their discharge rate only at stimulus sizes, which covered the receptive field centers. It appears that the excitatory (off-)mechanisms of the receptive field periphery are activated during alcohol withdrawal. Off-center-neurons behaved differently in this respect. Possible mechanisms underlying these observations are discussed.

Supported by th Deutsche Forschungsgemeinschaft Physiologisches Arnimallee 22.

(GR 161).

Institut der FU Berlin, D 1 Berlin 33,

R 114

227 WATER AND ELECTROLYTE EXCRETION DURINGACUTE REVERSIBLE MITRAL STENOSIS IN CONSCIOUS DOGSON A LOW SODIUM INTAKE PRETREATED WITH DOCA.-H.W.Reinhardt, G.Kaczmarczyk,B.Arnold,R.Eisele,J.Riedel,U.Kuhl,M.Gatzka,F.Eigenheer. Acute elevation of l e f t atrial pressure (LAP) in dogs increases renal water excretion (GAUERand HENRY).In conscious dogs kept on a low sodium diet LAPelevation leads to a substantial increase of sodium excretion (REINHARDT et al, PflUgers Archiv,Supp.355 R 52 (1975)). To exclude the possibility that this effect may be caused by a reduced adrenal hormoneactivity, 2 dogs were pretreated with 15 mg DOCAi.m. on 5 consecutive days 2 hours before the experiments were started. The method of LAP-elevation has been described elsewhere (s.o.).In control experiments on 4 conscious dogs on 15 days without DOCApretreatment, a rise in LAP of about 10 cm H20 leads to an increase of urine volume from 30 + 16 to 120 + 52/ul/min.kg (mean + 400%) and an increase of sodium excretion f r e D . 4 + 0.2 ~ 3.~+2.3/ueq/min.kg(mean + 780 %).with DOCApretreatment the correspo-nding values--wer6 a rise in urine volume ~ r ~ 7 to 120 + 20/ul/min,kg (mean + 320 %) and a rise in sodium excretion from 0.4 ~ 0-/2 tO 5.5 ~ 3.3/ueq/min,kg (mean + 1300 %). These data strongly suggest that natriuresis induced by an elevated LAP cannot be explained by decreased mineralocorticoid activity. The results point to the existence of a seperate sodium excretion system. Arbeitsgruppe Experimentelle Anaesthesie, Freie Universit~t Berlin, Klinikum Charlottenburg, 1 Berlin 19, Spandauer Damm130. 228 LACK OF EVIDENCE FOR A RELATIONSHIP BETWEEN LEFT ATRIAL PRESSURE AND RENAL BLOOD FLOW INCONSCIOUS DOGS.- G.Kaczmarczyk,H.W.Reinhardt,U.Kuhl,J.Riedel, R.Eisele and M.Gatzka An increase in renal blood flow (RBF) after elevation of l e f t atrial pressure (LAP) was suggested in anesthetized (ARNDT 1963) and conscious (LYDTIN 1964) dogs. Methods: In order to reevaluate this effect, 20 experiments were carried out on ~ s (10.0+1.2 kg b.w.)kept on a high (14 meq Na/kg.day) or a low (0.5 meq Na/kg.day) sodium intake. After recovery from surgery (LAP catheter, purse string around the l e f t atrium, electromagnetic flowmeter around the l e f t renal artery), LAP and RBF were,measured simultaneously 1)postprandially (pp) for 180 minutes 2)during experimental elevation of LAP by tightening the purse string, and 3) during acute plasma volume expansion (5ml/kg colloid solution iv for 30 minutes). Results: 1)In dogs on a high sodium intake, pp RBF and LAP increased without ~ a n y correlation in the course of their rise. In dogs on a low sodium intake, pp RBF increased, LAP did not. 2)RBF (control 13.0+3.3 ml/min;kg) did not change when LAP was elevated by 4.0+1.3 cm H20 for 60 minutes, and further increased by 10.0+2.7 cm HO0 for 60 minutes. 3)During colloid infusion, LAP increased;by 4.0+~,1 cm H2~, RBF did not change, however. After colloid infusion RBF increased c~siderably (4 RBF+32+17 %).A direct response of RBF to an increase of LAP was never observed.Th~efore i t seems doubtful that an elevation of LAP causes an increase of RBF in conscious dogs. Arbeitsgruppe Experimentelle Anaesthesie, Freie Universit~t Berlin,Klinikum Charlottenburg, 1 Berlin 19, Spahdauer Damm130

R 115 229 EFFECT OF PENTAGASTRIN ON RENAL BLOODFLOWIN CONSCIOUS DOGS.M.Gatzka,H.W.Reinhardt,K.Fahrenhorst,G.Kaczmarczyk,J.Riedel,and U.Kuhl

Renal blood flow (RBF) was shown to increase postprandially (pp) in conscious dogs independent of sodium content of the diet.(PfIUgers Archiv 354, 287-297, (1975)).Although volume receptors may be involved, the mechanismo--o-f-this pp RBF increase remains far from clear. Pp augmentation of plasma levels of gastrointestinal hormones (GIH) and the capability of GIH to increase mesenter i c blood f]ow are well documented. This study investigates the possible influence of GIH on RBF, using Pentagastrin (PG) as a substitute. Methods: Six conscious female dogs (9,2-18,7 kg BW) kept on a high sodium diet ~ k g day) were examined for a total of 24 times beginning 2 weeks or more after implantation of an electromagnetic flow probe around the l e f t renal artery.After recording fasting control values for at least 1 h, PG 1,2ug/kg.h was infused i . v . for 60 min dissolved in not more than 30 ml 0,9 % NaCI. Infusion of NaCl without PG was given to 4 dogs as a control experiment. RBF, heart rate (HR), and urine excretion (~) were measured for 180 min. Results: Fasting controls were RBF: 9,6 + 2,5 ml/min kg, and HR: 68 + 10. RBF increased in a l l experiments with PG in~sion, reaching a maximumof-56 + 27% after 92 + 31 min. At the RBF maximum HR was 77 + 9 (+13 %). Changes in RBF and were n ~ correlated. During NaCl control experTments RBF remained stable within + 12 %. These ~ s u l t s suggest that pp GIH levels may be involved in pp RBF increase. Arbeitsgruppe Experimentelle Anaesthesie, Freie Universit~t Berlin,Klinikum Charlottenburg, 1 Berlin 19, Spandauer Damm130. 230 THE SEPARATE AND COMBINED EFFECTS OF COMMON CAROTID OCCLUSION AND NONHYPOTENBIVE HEMORRHAGE ON HIDNEY BLOOD FLOW IN THE UNANESTHETIZED DOG. R.Gross~H.Ruffmann~and H.Kirchhelm Afferent pathways from both the low- end high pressure regions of the cardiovascular system seem to be involved in the regulation of renal blood flow (Oberg and Whlte,Acta physiol, scand.SO,383,1970; Mancia et al.,Circ.Res.}),?13,1g?3). The effect of common carotid occIusion (CCO) and non-hypotenslve hemorrhage on kidney blood flow (RBF) (electromagnetic flowmeter), kidney perfuslon pressure bn the abdominal aorta (ABP), carotid sinus pressure (CSP), central venous pressure (CVP), and heart rate (HR) were recorded in the trained resting dog. A pneumatic cuff around the abdominal aorta was used to keep ABP close tothe control level during COO. Hemorrhage (15 ml/kg) reduced CUP by 1.6 mmHg but caused no significant changes in ABP and RBF. Under control conditions CCO induced a reduction of CSP by 29 mmHg, increased ASP by 24 mmHg, and elevated HR by 6 beats/mln., RBF was not changed significantly whether observed when ABP was allowed to rise or when ABP was kept constant. After hemorrhage CCO caused similar changes in CSP, ABP, and HR; again RBF was not changed significantly neither with increased ABP nor with ASP kept constant. In the same anlmai emotlonai excitement (gun shot) induced a reflex renal vasoconstriction which was completely abolished folloulng o~adrensrgic blockade. It is concluded that the task performed by the kidney in volume reguiatlon does not necessarily involve a reflex reduction in total blood fiow to the organ. 1. P h y s i o l o g i s c h e s I n s t i t u t , 6 9 , H e t d e l b e r g ,

Im Neuenheimer Feld 326

R 116 231 Na-excretion and renal Na-K-ATPase activity of hypertensive rats maintained on Na-free diet M, M~yusz, I. Mehnert and R. R~del

Previous experiments demonstrated marked disturbances in the electrolyte balance of rats with Goldblatt-type hypertension characterized by increased salt appetite, Na-excretion rate and renal ATPase activity. In order to evaluate the role of eachof these factors, Goldblatt-rats with one clamped renal artery and both kidneys in situ were put on Na-free diet for 7-8 days. Na-excretion rate of normotensive control rats reached a minimum (13 uEg/IOO g body weight x 24 h) within 5 days and was maintained on this level henceforth, whereas Goldblatt-rats continued to excrete significantly higher amounts of Na (35 uEg/lO0 g body weight x 24 h). At the end of the experiment no difference in kidney weight or in the amount of membrane protein between control- and Goldblatt-rats could be detected. However, in salt-free fed control rats total renal Na-K-ATPase activity was found elevated by about iO % as compared to animals maintained on normal laboratory chow. In contrast to this, Goldblatt rats on Na-free diet showed sharply reduced renal Na-K-ATPase activity. In all animals studied the amount of Na excreted during 24 h at the end of the experiment showed a close, indirect correlation with the total Na-K-ATPase activity present in the kidneys. Physiologisches Institut der Universit~t Kiel, D-23 Kiel 1, Olshausenstr. 40/60 232

SUBSTRATE PREFERENCES OF ISOLATED RAT KIDNEY CORTEX CELLS G. Gronow, G. Randzio and Ch. Weiss The 14CO 2 production from exogenous 14C_U labelled substrates has been measured with a preparation of rat kidney cortex cells isolated by collagenase. Without exogenous substrates the cells took up 1218 rcnoles oxygen / m g DNS x rain. Upon addition of glucose ( 5.5 mM ) oxygen consumption rose by 2i%. Neither exogenous nor newly synthetized glucose was metabolized to respiratory carbon dioxide. Offering a mixture of substrates in physiological concentrations ( -~Im~ lactate (Lac) supplied 36.6%, glutamate (Glu) 29.2%, malate (Mal) I0%, acetate (Ac) 7.2%, palmitate 7%, pyruvate (Pyr) 4%, oleate 3.8%, and propionate (Prop) 2% of the labelled carbon dioxide production (=I501 r~oles / 1930 nmoles oxygen / mg DNS x rain). From a mixture of substrates which contained no long chain fatty acids but 2mM of each substrate 22.4% of the labelled carbon dioxide (I665 r~noles / 2500 r~noles oxygen / m g DNS x rain) were derived from 2-ketoglutarate (2-KG), 22.3% from Pyr, 20.5% from succinate (Succ), 13.5% from Mal, 8.5% from Glu, 5.6% from Lac, 4% from Ac, 2.2% from Prop and only I% from citrate. If 3 preferred substrates were offered (2 mM each), 39.5% of the labelled carbon dioxide (I735 r~noles / 2760 r~oles oxygen / m g DNS x rain) were derived from Succ, 34.4% from Pyr, and 26.2% from 2-KG. If Succ, Pyr and 2-KG were offered as sole substrates (2 mM) only 652-901 r~oles labelled carbon dioxide (per 1870-2320 mnoles oxygen / m g DNS x rain) are obtained. The results indicate that in the oxidative energy metabolism of the rat kidney cortex long chain fatty acids can be replaced by other substrates and that a combination of Krebs cycle intermediates stimulating respiratory activity may replace a large number of physiologically available substrates. Department of Physiology, University of Kiel, D 23 Kiel, OlshauserLqtr. 40-60

R 117 233

INTRAVITAL MICROPHOTOHETRY OF A FLUORESCENT DYE SECRETED BY THE RENAL TUB.ULES M. S t e i n h a u s e n , P. M i i l l e r a n d N. P a r e k h On t h e k i d n e y c o r t e x s u r f a c e o f r a t s , late proximal tubule loops are situated around the welling point (the branching p o i n t oT a n e f f e r e n t arteriole), whereas early proximal loops lie at a distance from the welling point ("cortical counterC u r r e n t s y s t e m " ) . We o b s e r v e d b y i n c i d e n t light microscopy the accumulation of the fluorescent dye a c r i f l a v i n starting from the welling point into the late proximal loops (see Film d e m o n s t r a t i o n ) . We h a v e a l s o d e m o n s t r a t e d t u b u l a r s e c r e t i o n of the fluorescent dye s u l f o n e f l u o r e s e e i n in clearance experiments and by incident light microphotometry. For the latter m e a s u r e m e n t s we u s e d a M P V - M i c r o s e o p e p h o t o m e t e r ( L e i t z ) , Ultropak optics, ~o illuminator (Leitz), and x e n o n lamp illumination. The e x c i t a t i o n l i g h t h a d a w a v e l e n g t h o f &70 nm. Under c o n t r o l c o n d f t i o n s dye c o n c e n t r a t i o n between the middle of the early and the middle of the late proximal tubule loops i n c r e a s e d b y a f a c t o r o f 2 . 1 9 ~ 0 . 2 0 SEM ( n = i T ) . W i t h p r o b e n e c i d , an inhibitor of organic acid secretion, t h i s f a c t o r was significantly decreased (~<0~01) to i.56~0.003 (n=iO). This s t u d y shows t h a t i t i s p o s s i b l e t o make d i r e c t q u a n t i t a t i v e measurements of tubular secretion on t h e r e n a l c o r t e x s u r f a c e of the rat without micropuncture. I. Physiologisches Institut, UniversitRt Heidelberg, D 69 Heidelberg, Im N e u e n h e i m e r F e l d 326 Supported by Deutsche Forschungsgemeinschaft (SFB 9 0 ) 234 FILM DEMONSTRATION: CORTICAL RAT KIDNEY M. S t e i n h a u s e n

YESSEL

AND TUBULAR

S Y S T E M OF THE

To show t h e p r o x i m a l t u b u l a r b l o o d s u p p l y i n t h e r e n a l c o r t e x of rats, ~he following techniques are demonstrated in this film: 1. I n t r a v i t a l fixation of the whole kidney followed by casting of the arterial system and clearing of t h e t i s s u e . 2. C a s t i n g of single nephrons by micropuncture in combination with casting of the vascular system with differently colored plastics. 3. Intravital fixation of the whole kidney, retrograde casting of tubules from the renal pelvis and casting of the arterial system with differently colored plastics. ~. C a r t o o n o f t h e cortical v e s s e l a n d t u b u l a r ~system w i t h t h e c o u r s e o f t h e b l o o d a n d u r i n e f l o w a n d dye p a s s a g e s . 5. I n v i v o m i c r o c i n e m a t o g r a p h y o f t h e r e n a l s u r f a c e a n d , b y way o f l i s s a m i n e g r e e n p a s s a g e s , demonstration of the grouping of proximal tubules. 6. I n t r a vital fluorescent microcinematography to locate secretion of dye from t h e w e l l i n g p o i n t s i n t o l a t e p r o x i m a l t u b u l e s . The film confirms our previous observations that in the rat kidney the branching.points of the vasa efferentia (the so-called welling point) are situated next to the late proximal tubular l o o p s . On t h e o t h e r h a n d , e a r l y p r o x i m a l t u b u l a r l o o p s w h i c h a r e c l o s e t o t h e g l 0 m e r u l i l i e a l o n g way o f f t h e w e l l i n g p o i n t s and are therefore supplied by blood with a lower oxygen tension. T h e mean d i r e c t i o n of proximal tubular urine flow in the rat kidney is therefore opposed to that of the peritubular blood flow (cortical counter-current system). I. Physiologisches !nstitut, Universit~t Heidelberg. Im N e u e n h e i m e r F e l d 326

Heidelberg,

D 69

R 118 235 EFFECT OF PARATHYROID HORMONE ON THE ACTIVE CA++-REABSORPTION IN THE PROXIMAL CONVOLUTION OF THE RAT KIDNEY K.J.Ullrich, G.Capasso, G.Rumrich and S.KlSss Parathyroid hormone (PTH) was shown to augment the Ca ++ reabsorption from the renal distal tubule (Widrow and Levlnsky, J.Clin. lnvest.]2,2152,]962) as well as from the intestine (Birge et al. J.Clln. Invest.54,702,1974). The data about its effect on the proximal convolutlon, however, are controversial (Kuntziager et al. Am.J. Physiol. 227,905,1974). To clarify this, we determined with stop flow microperfusion and simultaneous capillary perfusion the transtubular concentration difference (Ac) of Ca ++ and of CI- at zero ne~ flux of solutes and water as well as the Ca ++ permeability. Since Cl-was shown to be distributed passively we could calculate from the CI- distribution ratio the transtubular electrical potential difference (p.d.). In 2-5 days parathyroldectomlzed rats a lumen positive p.d. of 2.5 mV was calculated, which dropped I hr after application of PTH to 1.6 mV. The traastubular Ac of Ca ++ was 0.36 mmol/l in PTX animals and 0.50 after PTH. The transtubular electrochemlcal potential difference An for Ca ++ was 0.]4 and 0.29 n~ol/1 respectively. The correspondent permeability values for Ca ++ were ]2.2 and lO~Sxl0-Ycm2 /sec. Using the equation Jact = P.An, an active Ca ++ transport rate of O. 17xlO-llM/cm.sec was calculated for PTX rats and one of 0.27 after substitution with PTH. The data indicate that PTH increased the active transport rate for Ca ++ in the proximal tubule. If the different p.d. prevails also under free flow conditions, the reduced active Ca ++ reabsorptioa in PTX animals can be compensated by a higher passive Ca ++ reabsorption. Max-Planck-Instltut f~r Biophysik, D 6000 Frankfurt/M., Kennedyallee 70 236 ACETAZOIAMIDE INHIBITS PASSIVE BUFFER EXiT FROM BAT KIDNEY PROXIMAL TUBUIAR CELLS E. FrSmter, K. Sato and K. GeBner

Sudden removal of peritubular bicarbonate from proximal tubule of rat kidney causes a sudden transient depolarization of the peritubular cell membrane,which indicates that this membrane is highly permeable to HCO 3 buffer(E.FrSmter et el. Symp.Med.Hoechst p 119, 1971 and K. Sato, Pf]Ggers Arch.347,R32 1974). To obtain further insight into the mechanism of HC0~permeation we have performed experiments with other buffers and with the car~bonic anhydrase inhibitor acetazolamide. It was found that the effect of HCO 3 can be mimicked by other lipid soluble buffers such as glycodiazine, or butyr~te but not by phosphate buffer. This suggests that the buffer permeability depends on the lipid solubility of the undissociated component and that the buffers penetrate in form of the ~ndissociated acid(along the hydrophobic region of the membrane)and OH (or H in opposite direction)along a specific transport site. Application of acetazplamide(O. I to I mmol/1)diminished the electrical potential response to changes of peritubular HCO~ (reduction of tHCO~), increased the response to changes of peritubular K cGncentrations(increa~e of tz)and revealed a small but significant depolarization upon replacement of Cl'~by SOb(increase of tel)which indicates a small C1 permeability that is not observable under cont~S1 conditions. Furthermor@ acetazolamide increased the peritubular cell membrane resistance by 22% but left the transepithelial resistance unchanged. Similar effects were observed if acetazolamide was applied with all HC0~ being replaced by glycodiazine or butyrate. The data indicate that acetazolamide blocks the bicarbonate p~rmeability of the peritubular cell membrane possibly by inhibiting an OH-(or HT)permeatlon site. Max-Planck~Institut ffir Bi~physik, 6 Frankfurt/Main , Kennedyallee 70

R 119 237 ELECTRICAL STUDIES ON AMINO ACID TRANSPORT ACROSS BRUSHBORDER MEMBRANE OF RAT PROXIMAL TUNJLE IN VlVO I. SamarZija and E. FrSmter

The mechanism of amino acid t r a n s p o r t in r a t proximal tubule was studied by applying d i f f e r e n t amino acids from the t u b u l a r lumen and measuring the response of the transepithelial potential difference and of the.cell membrane potential. The neutral L-phenylalanlne, the positively charged Lornlthlne and L-lyslne and the negatively charged L-aspartate and L-glutamate were investigated at physiological pH. If applied together with Na in the tubular lumen all three groups were found to depolarlze the potential difference across the luminal cell membrane and to make the tubular lumen electrically more negative. These effects were absent during luminal perfusion with choline Ringer's solution. The data indicate that the coupling site between Na and amino acid flux is located in the luminal cell membrane for all amino acids tested, including ornlthine and lysine which encounter a favourable electrical gradient across the luminal cell membrane but an adverse gradient across the peritubular membrane. The negatively charged amino acids appear to be transported with more than one Na ion per molecule. In further experiments a distinction between individual transport systems was attempted by studying whether the potential response to simultaneous application of different amino acids was additive or not. An additive response was observed between L-oraithine and L-phenylalanine but not between L-ornithine and L-lysine. The data confirm the contention that positively and neutraly charged amino acids are transported by separate transport mechanisms. M a x - P l a n c k - l n s t i t u t f u r Biophysik, D 6000 Frankfurt/M., K~nnedyallee 70 238 PHE~INE TRANSPORT BY ISOLATED PENAL PLASMA HEMBRANEVESICLES M. Thees and R. Kinne

J . Evers,

Osmotloally r e a c t i v e v e s i c l e s from r e n a l brush border m i c r o v i l l i (BBM) and b a s o l a t e r a l plasma membranes (BLM) were i s o l a t e d from r a t kidney c o r t e x homogenates (H.G. Heidrich et el., J. Cell Biol. 54, 232, 1972). Uptake of Lphenylalanlne into these vesicles were determined according to Hopfer et al. (J. Biol. Chem. 248, 25, 1973). In the absence of a n y l o n gradient or with an inward directed KCl gradient an exponential influx of L-phenylalanlne into B~M was observed until equilibrium was reached. If, however, an inward gradient of Na + - with a permeable anion , was present, the intravesicular L-phenylalanlne concentration became transiently larger than at equilibrium. This "overshoot" was augmented up to 6 times if an intravesicular negative electrical potential difference was superimposed. The latter was obtained by prefilllng the veslcles with K2.S04.and. adding valinomycin, to the. test solution. . . L-phenylalanine uptake was inhiblted by p-azldophenylalanlne. By pref111zng the vesicles with inactive L-phenylalanine an exchange diffusion either in the presence or absence of an ion gradient was seen. BLM also take up L-phenylalanlne but without overshoot, only a small effect of sodium and a small exchange diffusion is observed in these membranes. The data indicate an eleetrogenlc Na + phenylalanlne cotransport through the brush border membrane. M a x - P l a n c k - I n s t i t u t f ~ r Biophysik, D 6 Frankfurt/M., Kennedyallee 70

R 120 289 RENAL HANDLING OF L-METHIONINE AND OTHER N E U T R A L A M I N O A C I D S S T U D I E D B Y C.qNTINUOUS MICROPERFUSION~S~Silbergagl . . . . Recently Bartscocas et al. (Pediat.Res.8, 673 (1974)) concluded from their in vitro data that L-methionine (=L-Met) is reabsorbed by a specific tubular reabsorption mechanism which does not accept other naturally occuring amino acids. In order to test this conclusion in vivo et situ single proximal convolutes of the rat|kidney were continuously perfused with equilibrium solutions containing 4C-labelled amino acids. ReSUlts:L-Met as well as L-iso-leucine or L-tryptophan can inhibit reabsorption of L-phenylalanine, whereas L-proline does not show this effect. If L-Met uptake is measured a fast reabsorption of this amino acid is apparent at an initial concentration of 0.3 mM. Raising this concentration to 3 mM does not change fractional reabsorption rate. This rate was reduced only at an initial methionine concentration of 30 mM. Addition of 30 mM D-Methionine or 20 mM L-Homoserine did not affect reabsorption of 0.3 mM L-Met. In contrast, addition of 20 mM L-phenylalanine or L-iso-leueine caused a marked inhibition of L-Met transport. CondluSiOns:These data clearly indicate that there exists a common transport system for L-Met and L-phenylalanine in the proximal tubule of the rat. From other work (Chanet al. Amer.J.Physiol.22|,575 (1971))and recent results of this laboratory(Silbernagl, PflOgers Arch.353,24] (]975))it can be concluded additionally that also cycloleucine, tryptophan and perhaps isoleucine share this mechanism. The capacity of this transport receptor seems to be relatively high, because saturation becomes apparent only at concentrations much higher than 3 mM. The contrast to the in vitro data mentioned above can therefore readily be explained by the fact that the maximum concentration of amino acids used in that study (2.4 mM) was not high enough to inhibit or saturate cellular uptake of L-Met. Physiologisches Instit.der Univ.,SchSpfstraSe 41, A-6020 Innsbruck,Austria

240 L-PROLINE REABSORPTION IN RAT KIDNEY TUBULES. MICROPERFUSION EXPERIMENTS. H. V~ikl, S. Silbernagi Infusion of L-proline into dogs increases urinary excretion only of L-serine but not of glyeine and other amino acids (Webber, Am.J.Physiol~202,577 (1962)). On the other hand, in hyperprolinemic patients also excretion of glycine and of some other neutral amino acids is increased. Addition~lly it is well known that homocygotes of renal iminoglycinuria show elevated excretion of imino acids + glycine, whereas in heterocygotes only excretion of glycine is increased (Tancr~di et al., J.Pediatr.76,386 (1970)).HFinally an isolated renal glycinuria was observed (De Vries et al., Am.J.Med~23, 408 (]957)). In order to obtain more in vivo data of renal handling of L-proline and glycine, single proximal tubules of rat kidney were continuously perfused with equilibrium solutions containing ]4C-labelled L-proline. Results: At an initial concentration of 2 mML-Proline is reabsorbed relatively slowly compared to other amino acids: At a perfusion distance of ] ~nn fractional reabsorption raEe of L-proline is less than 50 %. Raising the concentration to 20 mM decreases this rate to about 20 %. Uoneluslons: L-Proline reabsorption in rat proximal tubules is~aturable. Passive diffusion of this imino acid through the tubular wall seems to play a less important role than it was shown with glycine (Silbernagl et al., PflHgers Arch., 323, 342 (1971~. Physiologisches Institut der Universit~t Innsbruck, Sch~pfstraSe 41 A - 6020 Innsbruck, Austria

R 121 241

WHICH TUBULAR MEMBRANE LIMITS AEGININE REABSORPTION IN THE RAT KIDNEY ? W. Pf~ller~. S. Silbernagl, H. Mairb~url ..... Many data concerning the transport kinetics of amino acids are available from m/cropuncture studies and also some from investigations with the "Chinard" technique. In all these studies one question has not been answered directly - the localization of the specific amino acid receptors on the proximal tubular cell. Therefore a histochemical method was applied which should make it possible to visualize free amino acid distribution at the cellular level. For this purpose an effect well known from autoradiographic studies of protein biosynthesis was exploited, which is caused by the cross linking of free amino acids by glutaraldehyde via their amino orBguauidino-groups. Utilizing this reaction by perfusing single nephrons with H-Arginine containing solution and subsequently with 5% buffered glutaraldehyde a certain distribution pattern of labelled arginine could be demonstrated within the tubular cell. When the reabsorption of arginine is competited by unlabelled lysine a much smaller amount of labelled arginine appeared within the proximal tubular cell. Amino acids not reabsorbed by the arginine - lysine system do not influence the entrance of arginine into the cell. Therefore receptors limiting arginine reabsorption are concluded to be localized on the luminal plasma membrane. To demonstrate the glutaraldehyde cross linking as representation for the real distribution the t6tal experiment was control~d by a cryopreparation which needs no use of a chemical fixative. AdditionaS~the arginine binding sites are localized by electron microscopic autoradiography. Institute of Physiology, University of Innsbruck, Sch6pfstraBe 41, A-6o2o Inusbruck, Austria. 242 QUANTITATIVE MORPHOLOGY OF RAT KIDNEY CORTEX. M.. Rittlnger,. W. Pf~ller~ P. Deetjen. In order to obtain data which can be used as reference values for calculation of traaspor~ kinetics, the stereologic organization of rat kidney cortex was estimated light- and electron microscopically by using vascular perfusion fixation. Immersion fixation is not usefull when cellular membrane surface areas referred to unit volume protoplasm should be evaluated because the collapse of the tubules following an immersion fixation will change the reference value strikingly in comparison to the in vivo situation. Perfusion fixation will be also the most suitable method when the quantitative architecture of kidney cortex should be investigated generally. Results: A significant decrease in tubular luminal volume can be demonstrated if superficial parts of kidney cortex are compared with deeper regions (-5o%, p
R 122

243 THE EFFECT OF VOLUME EXPANSION ON THE DILUTING CAPACITY OF A S C E N D I N G L I M B S (AL) O F H E N L E ' S L O O P IN V I V O H.-U. Gutsche, R. Mfiller-Suur~ K. Hierholzer with techn, ass. of I. Lichtenstein T h e capacity of A L to dilute the tubular fluid w a s tested in mieropuncture experiments on rat kidney surface n e p h r o n s . T h e loops w e r e functionally isolated in vivo by m e a n s of late proxima4 solidparaffin blocks and perfused with proximal equilibrium solution (NaCI I 10 m M / l , mannito190 m M / l ) , in orthograde direction using a pressure contr011ed microperfusion system. Pulsed interruptions of the 50 to 75 nl/min perfusion rate a% varying intervals f r o m 5 to 180 sec led to equilibration of tubular fluid in the different segments of the loop. After reestablishment of perfusion, fluid equilibrated in A L w a s propulsed into the earliest accessible distal surface segment, w h e r e its total electrolyte activitiy w a s monitored continuously with a microconductivity probe. In eontrolrats the m i n i m a l conductivity (Kmin, as equivalent N a C I concentration i n m M / l at 37oC) of the ascending limb T F w a s K m i n = 3 9 . 5 + 3 . 6 SE, n=10, established with tl/2 =4.5see.Acute v o l u m e expansion (16 ml/h, 0 . 9 % N a C l ) l e d only to an insignificant change of diluting capacity, with slightly elevated values (Km~n=45.. 6 + 3.5, ti/2=4.8 sec, n=8). Intratubular perfusion with furosemide (10-~M) impaired significantly the diluting capacity: K m i n = 5 3 . 3 + 3.2, tI/2=31 see, n = 6 . F u r o s e m i d e in acute v o l u m e expansion led to further impairment. It is confirmed that furosemide is a potent inhibitor of electrolyte transport in the thick ascending limb. Acute v o l u m e expansion alone, however, does not result in impaired diluting capacity. T h e present m e t h o d allows direct exploration of the diluting capacity in a s e g m e n t which has not readily been accessible to micropuncfure. Inst. f. K H n . Physiologie, F U Berlin, D - 1 Berlin 45, H i n d e n b u r g d a m m 30 244

F U N C T I O N OF THE LOOP OF H E N L E D U R I N G D E V E L O P M E N T . S T U D I E S BY M I C R O P U N C T U R E ON S U P E R F I C I A L N E P H R O N S H. Zink and M. H o r s t e r M a t u r a t i o n a l c h a n g e s of c o u n t e r c u r r e n t f u n c t i o n hav@ so far been d e s c r i b e d from t i s s u e solute and c l e a r a n c e a n a l y s i s only, w h e r e a s the d e v e l o p m e n t of i s o t o n i c fluid t r a n s p o r t has p r e v i o u s l y been s t u d i e d in single p r o x i m a l t u b u l e s in situ and in vitro. Loop of H e n l e f u n c t i o n in s i n g l e s u p e r f i c i a l n e p h r o n s b e t w e e n day 14 to 21 (n=ll) and day 25' to 35 (n=7) of p o s t n a t a l age in rats kept on a h i g h N a - d i e t d u r i n g p r e - and p o s t n a t a l p e r i o d was s t u d i e d by c o n v e n t i o n a l m i c r o p u n o t u r e and m i c r o d i s s e c t i o n t e c h n i q u e s w h i l e k i d n e y GFR, Na and total s o l u t e e x c r e t i o n , and s y s t e m i c a r t e r i a l p r e s s u r e were m o n i t o r e d . N e p h r o n f i l t r a t i o n rate i n c r e a s e d l i n e a r ly w i t h age and was for a g i v e n n e p h r o n i d e n t i c a l in early d i s t a l (ed) and late p r o x i m a l (ip) d e t e r m i n a t i o n . A b s o l u t e fluid a b s o r p tion b e t w e e n ip and ed site (loop of Henle) i n c r e a s e d by a factor of 2 . 5 ! b e t w e e n 0.2 and 0.4 g of k i d n e y weight. A b s o r p t i o n as a f r a c t i o n of the v o l u m e load d e l i v e r e d to the loop of Henle inc r e a s e d s i g n i f i c a n t l y from a b o u t 34 t o 50% w h i l e p r o x i m a l t u b u l e v o l u m e load to the loop i n c r e a s e d f r o m 3.8 to 6.7 n l / m i n d u r i n g this e a r l y m a t u r a t i o n . A b s o l u t e v o l u m e a b s o r p t i o n per unit length of loop of H e n l e i n c r e a s e d by a factor of 1.67. S i m u l t a n e o u s l y , o s m o t i c p r e s s u r e of the fluid e m e r g i n g from the loop of Henle dec r e a s e d s i g n i f i c a n t l y by a b o u t 50% from close to i s o t o n i c at the e a r l y :phase of m a t u r a t i o n . We c o n c l u d e that v o l u m e a b s o r p t i o n in the loop of H e n l e i n c r e a s e s d i s p r o p o r t i o n a t e l y to the i n c r e a s i n g loop v o l u m e load d u r i n g mat u r a t i o n . The a b i l i t y of H e n l e ' s loop to g e n e r a t e h y p o t o n i c f~uid is a t t a i n e d only g r a d u a l l y d u r i n g m a t u r a t i o n . D e p a r t m e n t of P h y s i o l o g y , U n i v e r s i t y of M u n i c h . Munich, Germany.

R 123

245 INFLUENCE OF LUMINALLY ADMINISTERED AMILORIDE, OUABAIN, AMPHOTERICIN B ON PERITUBULAR MEMBRANE POTENTIAL AND VOLUME REABSORPTION IN THE DISTAL TUBULE. L. Hansen, U. Teuscher, G. Giebisch, and M. Wiederholt

AND NET

F o r f u r t h e r c h a r a c t e r i z a t i o n of the t r a n s p o r t p r o c e s s in the dis~al t u b u l e of A m p h i u r a p e r i t u b u l a r m e m b r a n e p o t e n t i a l (PD) was r e c o r d e d while l u m i n a l p e r f u s i o n r a p i d l y c h a n g e d f r o m I00 m M NaCI to 100 m M NaCI p l u s a m i l o r i d e , ouabain, o r a m p h o t e r i c i n B. A m i l o r i d e (10-4M) d e P o l a r i z e d the PD by 1 5 . 4 r n V f r o m 7 4 . 2 + 2 . 9 mV to 5 8 . 8 + 2 . 5 m V ( p ~ 0.001). Ouabain (10"5M) y i e l d e d a s o m e w h a t s-mailer e f f e c t , d e c r e a s i n g PD by I 0 . 4 mV f r o m 7 3 . 9 + 2.7 mV to 6 3 . 5 + 2 . 3 mV (p ~ 0.01). T h e e f f e c t s of both i n h i b i t o r s a p p e a r e d w i t h i n a few s e c o n d s and w e r e f u ll y and r a p i d l y r e v e r s i b l e . A m p h o t e r i c i n B ( 2 0 / u g / m l ) did not change the PD u n d e r t h e s e c o n d i t i o n s . R e a b s o r p • halft i m e s w e r e m e a s u r e d with the s p l i t - o i l d r o p l e t m e t h o d in o r d e r to e v a l u a t e the a c t i o n of the a g e n t s on net v o l u m e t r a n s p o r t . In c o n t r o l t u b u l e s a h a l f t i m e of 254 + 13 s e e (n = 20) was obtained. L u m i n a l a p p l i c a t i o n of o u ab ai n p r o l o n g e d th~ h a l f - t i m e to 492 + 36 s e a (p ~ 0. 001), w h e r e a s am p h o t e r i c i n B s h o r t e n e d it t o 188 + 13 s e e (p ~-0. 005). T h e r e s u l t s d e m o n s t r a t e that both a m i l o r i d e and o u a b ~ n a r e able to d e p o l a r i z e the p e r i t u b u l a r m e m b r a n e by d e c r e a s i n g l u m i n a l s o d i u m e n t r y into the c e l l . A m p h o t e r i e i n B e n h a n c e s net v o l u m e t r a n s p o r t by i n c r e a s i n g l u m i n a l s o d i u m uptake. Institut ffir K l i n i s c h e P h y s i o l o g 2 e , F r e i e U n i v e r s i t ~ t B e r l i n , D i B e r l i n 45, H i n d e n b u r g d a r n m 30.

246 An alternatlva model to study glomerulotubu!ar balance mechanism D. K. H~berle olume reabsorption rate (~), fractional volume reabsorption TF/PIn) and single nephron filtration rate (SNGFR) wer~ determined in aarly to middle (group I) and in lata (group 2) proximal tubular segments~ when their loops of H e n l e w e r e perfused artificially at low (appr. 5 nl/min) and at high (25 - 30 nl/mi~ flow rates. Puncture sites were localized by Latex injections and microd~ssection. In order to detect uncomplete volume collection 3H-inulin recovery was determined in 13 of 30 studied nephrons (group 2) by the infusion of 2 or 3 nl/min of a 3H-inulin Ringer solution into the tubules proximal of the collection site~ Results: During the loop perfusionSNGFR decreased from 32,8"+ 6,3 nl/min g K.W. (S. D., group I) to 18,4 + 517 nl/min g K~W7 and from 41,2 u 7,9 nl/min g K.Wo (S. Do, g~oup 2) to 24,~ u 6 nl/min g K.W7 In parallel ~ decreased from 12,1 + 5,4 nl/mi~ g K. W. (S. D. group I) to 8,4 + 4,4 nl/min g Ko W7 and from 20,7 u 827 nl/min g K. W. (S. D.,-group 2) to 12,U + 6,9 nl/min g KT W. TF/PIn ratio increased from 1,67 + 028 to-2,14 • 0,9 (group ~) and from 2,05 + 0,6 to 2,25 + 0,~8. Only in group. ff this difference is significantly differere~t from zero(p~O,025) Using the data of both groups a highly significant correlation between the reduction of SNGFR and ~, both expressed as percentage of control, was found which is given by the regression ~ine Y = 1,15 X + 13 (r = 0,7~)o It is concluded, that SNGFR and ~ of each proximal tubular segment change in parallel, when SNGFR is varied by tubuloglomerular feedback mechanism~ Departm. of Physiol., Uni. of Munich, D 8, Pettenkoferstr 12

~

R 124 247 FACTORS INFLUENCING pH-MEASUREMENTS WITH MICRO-ANTIMONYELECTRODES

P. Quehenberger Micro-antimonyelectrodes have widely been used for in vivo pH-measurements as well as for bicarbonate determinations in tubular fluid samples. However, the reliability of these methodes has been questioned since several authors found these electrodes measuring inaccurate pH-values in bicarbonate solutions. Puschett and Zurbaeh (Kidney Int. 6: 81-91, |974) suggested that the degree of divergence may be dependent not only upon the amount of bicarbonate present in the solution but also on the C02-tension of the equilibration gas. This study was made in order to investigate this question. Micro-antimonyelectrodes were first calibrated in standard phosphate buffer solutions. Variation of the CO 2tension from 6 ~ Hg to 60 mm Hg did not cause significant changes in the obtained calibration curves. Bicarb0nate/NaCl-solutions of the same osmolality but different bicarbonate concentrations were equilibrated with different C02/air mixtures, the pH-values calculated from the Henderson-Hasselbalch equation and controlled by means of a:macrD-glasselectrode. All pH-values measured with the antimonyelectrodes were too low according to the phosphate buffer calibration. The differences were dependent upon the bicarbonate concentration, varying between O,l pH-unit for high concentrations (50mM) and 0,4 units for low ones (5-10mM). The CO?-tension seemed to play no important role since a linear millivolt/pH -relationship with about the same slope was obtained for all solutions when the bicarbonate concentration was kept constant changing the pH-values only by varying the C02-tension of the equilibration gas. In a seperate study also the influence of oxygen on the antimony electrode was investigated. We found a millivolt-deflection corresponding to about 0,3 pH-units, however decreasing slowly within some minutes, when the partial pressure of oxygen in the solutions was changed from 60 m m H g to 120 ~ n H g (high pressure-lower values). Institut f~r Physiologie, Sch~pfstr.41

A-6020 Innsbruek

248 ON THE L I N K A G E OF ACTIVE H + / H C O ~ - S E C R E T I O N WITH THE M E M B R A N E BOUND H C O 3 - A T P a s e ~ U.Wais, H.~nauf, W.Kreutz A' " t r a n s p o r t - l i n k e d enzym" should be localized in the plasma m e m b r a n e and should change its activity in p a r a l l e l to active transport+rate. Information is poor about such a correlation b e t w e e n H /HCO~ secretion and enzyme activity for the HCO~s t i m u l a t e d ATPffse. We therefore investigated the s u b m a x i l l a ~ y main duct and the renal co~tex tissue. Both tissues are capable of actively t r a n s p o r t i n g H /HCO[ and adapt their transport rates to changes of acid-base b a l ~ n c e ~ In the sa:livary duct it could be d e m o n s t r a t e d that there is more H C O ~ a c t i v e l y secreted in metabolic alkalosis, but less in metabolic scidosis, compared to the controls. These c h a n g e s in active transport are p a r a l l e l e d by changes in the activity of the d u c t a l H00[ stimulated ATPase, the correlation c o e f f i c i e n t r being 0.96. H o W e v e r , in renal cortical tissue, there was a _ drastic reduction in the activity of the m e m b r a n e - b o u n d HCO 5 A T P a s e in metabolic slkalosis, and a significant reduction mn metabolic acidosis. The data are in full agreement with the data of H + t r a n s p o r t in proximal t u b u l e s , r e p o r t e d by Ullrich et al. (PflHger's Arch. 4975, i~ press). The correlation c o e f f i c i e n t was d e t e r m i n e d to be 0.99. It is c o n c l u d e d that changes in active transport r a t e of H + / H C O [ reflect changes in the activity of t h e + m e m b r a n e - b o u n d H C O ~ - A T P a ~ e w h i c h may therefore be regarded as a H / H C O ~ t r a n s p o r t - l i d k e d en zyme. D e p a r t m e n t of Internal Medicine and B i o p h y s i c s , U n i v e r s i t y of V r e i b u r g , D 78 Freiburg, H u g s t e t t e r Sir. 55 S u p p o r t e d by DFG, grant Kn 158/5.

R 125 249

PLASMA RENIN CONCENTR~2ION IN WISTAR RATS OF DIFFERENT AGE. K. Hayduk and G. Riegger. Many laboratory data and especially enzyme activities are agedependent. Little is known about age-dependence of renin. Therefore, we studied plasma renin concentration (PRC) in rats of different age. PRC was measured with the micromethod of Boucher and coworkers. The results are expressed in ng angiotensin/ml plasma.h incubation, mean+BE. PRC was determined during the foTlowing conditions i n y o u n g (IOO-130g;n=6-8) and old (350-#OOg;n=6-8) Wistar rats. I. Acute sodium depletion induced by furosemide in rats kept on a normal diet. In young rats PRC was higher before (33.8_+4.7) and after furosemide (55.8+4.3) than in old rats (14.5+3.7 resp. 29.7+3.7; p(O.01). 2. SodiUm restriction of 6 days duratlon increased--PRC in young rats to 91.9+15.6, in old rats to ~7.2+13.6 (p~O.05). 3. Administration of ~rciprenaline increased PR~ in young rats from 60.7+d0.6 to 227.3+52.0~ in old rats from d5.2~1.3 to 106.9 +8.1 (p
~

250

D o e s the Kidney Contain Its Own Angiotensin I C o n v e r t i n g E n z y m e ? H e r b e r t D a h l h e i m and Hans Schweisfurth The postulate of i n t r a r e n a l angiotensin II (A II) f o r m a t i o n n e c e s s i t a t e s a suff i c i e n t l y high r e n a l c o n v e r t i n g e n z y m e (C. E. ) activity. The following i n v e s t i gations w e r e done to find out the o p t i m a l r e a c t i o n conditions and the r e n a l (R.) distribution of C . E . which w a s f l u o r o m e t r i e l y m e a s u r e d u s i n g the synthetic s u b s t r a t e b e n z y l o x y c a r b o n y l - P h e - H i s - L e u (S) and A I. Applying A ! the p H o p t i m u m w a s identical to that of the A I f o r m a t i o n with r a t r e n i n and h o m o l o g ous s u b s t r a t e . Using S the p H - o p t i m u m of p l a s m a , lung and t e s t i c u l a r C. E. (pH=8.0) w e r e significantly different f r o m R. C . E . (pH=6.0). The M i c h a e l i s Menten constant f o r R, C . E . and S (23.2 + 7 . 4 ~ M ) differed significantly f r o m t h o s e of lung C . E . (86.4 _+ 9.3~uM), p l a s m a C . E . (70.5 _+ 19.6~uM) and t e s t i c u l a r C . E . (36.9 + 17.4~uM). In c o n t r a s t to the lung o r p l a s m a C . E . the R. C . E . could be inhibited by Na9 E D T A ( 10 mlVI) to only 10%. C l - i o n s w e r e not r e quired. The C . E . i n h i b ~ o r SQ 20881 (70jug/m1) and also D F P r e d u c e d the R. C . E . to about 80%. T h e R. C . E . w a s m e a s u r e d in m i c r o d i s s e c t e d t u b u l a r s e g m e n t s (0.097 + 0.027 U/)ug), j u x t a m e d u l l a r y (0.077 + 0.033 U/)ug) and s u p e r f i c i a l j u x t a g l o m e ~ u l a r a p p a r a t U s e s (JGA" s) (0.070 _+ 0.O25 U/~ug). The J G A C . E . i n c r e a s e d in r a t s kept on a high salt diet and w a s r e d u c e d in salt r e s t r i c t e d a n i m a l s . In J G A ' s of e s c h e m i c k i d n e y s (30 rain. ) R. C . E . a c t i v i t i e s w e r e significantly (about twofold) h i g h e r than t h o s e of the c o n t r a l a t e r a l k i d n e y s . The r e s u l t s obtained d e m o n s t r a t e the existence of a r e n a l c o n v e r t i n g enzyme. D e p a r t m e n t of P h y s i o l o g y , U n i v e r s i t y of Munic, D - 8 0 0 0 MGnchen 2, P e t t e n k o f e r str. 12

R 126 251

IMPEDANCEMEASUREMENTS

ON NECTURUS GALLBLADDER. E.SCHIFFERDECE~R and

E. FROMTER

The electrical impedance of Necturus gallbladder epithelium was measured with sine wave currents in the frequency range of 0.05 to 30.000 cps. The measurements were carried out in a modified Ussing chamber, using a four-electrode technique and displaying voltage currents loops on an oscilloscope screen. With the epithelium bathed in NaCI Ringer's solution the impedance locus diagram displayed a regular semicircle with minimal depression of the center below the R-axis (~= 0.42+0.70). Since the high frequency resistance corresponded within limits of error to the chamber resistance and since no separation into two semicircles was obtained, the data were analysed ~n terms of a simple

PF~cal}~l~cmer~ttsYgglesdtngthot

thOe5~mmm~,coRtst115s+2o5 t~he TM mu~dsCa~ =

5.1_+0.9

(a) and

serosal (b) cell membranes are approximately equal. Using the voltage divider ratio R / ~ = 2.52_+0.8 obtained with microelectrodes on bladders of comparable resistance the data yleld capacltances of C= = 7.2 and ~ = 18.0 wF/cm 2 respectively. With the specific membrane capacitance of I ~F/cm 2, these figures agree well with cell surface estimates from electromicrographs. Neither unilateral reduction of ion concentration nor application of amiloride succeeded in separation of the individual time constants of the mucosal and serosal cell membrane and a second low frequency semicircle (T o = 0.39 s) which was observed during substitution of luminal Na by K could not be explained in terms of membrane structure. Induction of osmotic waterflow from serosa to mueosa increased the membrane resistance at constant capacitance and led to a depression of the semicircle of ~ = 13~ . This effect which did not occur with waterflow in the opposite direction is explained by a dispersion of time constants which results from the increase of longitudinal resistance along the collapsed lateral spaces. Max-Planck-Institut ffir Biophysik, 6 Frankfurt/Main, Kennedyallee 70 9

a

o

.

252 I N F L U E N C E OF DC C U R R E N T GALL BLADDER EPITHELIUM

.

F L O W ON E L E C T R I C A L I M P E D A N C E OF N E C T U R U S H.Goegelein, U.Hegel and P.Weskamp

Observation of e l e c t r i c a l l y i n d u c e d c h a n g e s in i o n c o n d u c t i v i t y of t i g h t as w e l l as l e a k y e p i t h e l i a ( N . B i n d s l e v et al.,J.Membr. Bio1.19,357,1974 and BBA ~2,286,1974) r a i s e d the q u e s t i o n to which extent ~irec~ current not only influences properties of cellular interspaces but a l s o of cell m e m b r a n e s . T h e r e f o r e epitheli~ capacity was considered an interesting parameter. Imped a n c e f u n c t i o n s of N E C T U R U S g a l l b l a d d e r w e r e r e c o r d e d in v i t r o between IHz a n d 10kH~. AC c u r r e n t d e n s i t y w a s ca. I O ~ A c m -2, DC c u r r e n t d e n s i t i e s r a n g e d u p to 1 . S m A c m - 2 in e i t h e r d i r e c t i o n . Control data for parameters of the e q u i v a l e n t p a r a l l e l AC c i r c u i t

were: Ro-R_ =Rp:(170~74)ncm 2, Cp=(3.611.0)pFcm-2,

fo=(3001110)Hz,

~(:angle o~supressed aro-center):(3.6~2.3) O. T i m e c o u r s e of i m p e d a n c e of o t h e r w i s e u n i n f l u e n c e d bladders showed a slow monot o n e c h a n g e of t h e s e p a r a m e t e r s . In ca. 100 m i n R p a n d fo i n c r e a sed b y ca. 4 0 % and 10% r e s p e c t i v e l y , w h i l e C~ d e c r e a s e d b y ca. 4 0 % ( a v e r a g e v a l u e s ) and~ d i d n o t c h a n g e s y s s Poison i n g the e p i t h e l i u m w i t h CN and I A A s i m u l t a n e o u s l y (3mM) d e c r e a sed R p a n d fo a n d i n c r e a s e d Cp. ~ c h a n g e d e r r a n e o u s l y . DC c u r r e n t (JDc,~Icm-2) s h o w e d no c e r t a i n e f f e c t b e l o w 30. B e t w e e n 70 a n d ca. 7 0 0 R p i n c r e a s e ~ w i t h JDC, a b o v e 1000 it d e c r e a s e d (serosa+). Cp d i d not b e h a v e u n a m b i g u o u s . Experiments suggest, h o w e v e ~ a decrease especially at JDC v a l u e s w h i c h g e n e r a t e P D ' s g r e a t e r t h a n 100 m V ( s e r o s a ~) a c r o s s the e p i t h e l i u m . Inst.f. Klin. Physiologie,FU

Berlin,

DI

Berlin

45,Hindenburgdamm30

R 127 253

THE INPLUENOE OF 2.4.6-TRIAMINOPYRIMIDINE ON N&-TRANSPORT IN FROG SKIN. W. Zeiske 2.4.6-Triaminop~Timidine (TAP) was zeported to block the cation fluxes through the ~ l l b l a d d e r shunt pathway. (J. H. Moreno, Nature 2~I, 150, 1974). In an attempt to investigate its effeot on transport 9athways in frog skin it was found the% TAP is cots as an Amiloride-like blocker of sodium uptake. The maximum blocking effect of TAP is at about 5 I0-2M, it's apparent Hioh&elis constant about 5 I0-4M (i.e. 1000 times less effeotive then Amiloride). Experiments, at different pH-values of the outer solutions have shown that TAP is effective in the cationic form {pKs about 6.7). At pH 5.5 it decreases short oirouit current and Na~onduotanoe, apparently by competition with Na-ions. Some oharaoteris%ios of the molecular structure of TAP suggest ohemioal relation to Amilorlde, Triameterene and similar Na our~ent blooking agents and therefore a similar blooking meohanism. II. Physiolgisohes Institut der Universi%~t des Sa&rlandes, Abt. Epithelforsohung, D665 Homburg (Scar). 254

ANALYSIS OF THE ~NORGANIC IONS IN THE SPERMATHECAL FLUID AND THEIR TRANSPORT ACROSS THE SPERMATHECALMEMBEANE OF THE HONEY BEE QUEEN APIS MELLIFICA CARNICA B. Ge~ner + and K. Ge~ner The spermatheca, in which spermatozoa can be stored for years, has Been punctured and its fluid analysed and compared with haemolymph. The potassium, sodium and calcium ion concentrations were determined By a flame-photometer and phosphate by the method of Fiske and Suhbarow. The chlorlde ion concentration was measured By the method of Ramsy (1955) and the osmolallty by zryoscopy. The analysed values are summarized in the following table: potassium sodium calcium phosphate chlorlde osmolallty (meq/l) (meq/l) (meq/l) (meq/l) ( m e q / l ) (mosm/l)~ sp.fluid 137.8 15.7 8.0 0.41 24 476 haemolymph 18.1 31.6 9.1 2.05 61 530 Furthermore the electrical potential difference (PD) was measured across the wall of the spermatheca. The mean PD was +19 mV • 8 mV, lumen positive. The data indicate that potassium is actively secreted into the lumen that chloride and phosphate are actively absorbed out of the lumen and that sodium is distributed passively. The transport behaviour of Ca++ cannot be evaluated from our data because the amount of bound Ca in the respective fluids is not known. Furthermore pH was measured with micro-pH-electrodes. The spermatheca fluid pH was 7.3 in a semldlurnal queen bee and increased to 8,5 in three days old and older queen bees while the haemolymph in comparison remained constant at pH 6.2. The K-rich alkaline spermathecal fluid is thought to be important both for the motillty and for the survival of the sperms in the spermatheca. Max-Planck-Institut for Biophyslk, D 6 Frankfurt/M., Kennedyallee 70 +Presently Battelle-Institut, D 6 Frankfurt/M., Am RBmerhof 35

R 128

255 First measurements 5ody chemoreceptor -an--~ pH conditions Acker,

of membrane potentials of cultivated carotid cells of rabbit and cat under controlled PO 2

H., Pietruschka,

F., LUbbers,

D.W.

Until now the role of the different cells in the carotid body during chemoreception is not very well known. Since by means of tissue culture it is possible to cultivate type I and type II cells of the cat and rabbit carotid body (Pietruschka 1973) we t r i e d w i t h this model to test the role of the membrane potential of these cells in chemoreception. In a perfusion chamber the cells can be superperfused with a modified Ringer solution (Hepes buffer solution) containing different PO 2 and pH values. The membrane potential is monitored by glas microelectrodes (tip diameter 0,5 /um, resistance 10 M/k, tip potential 0 - 2 mY). The POp is co~trolled by PO~ microelectrodes very close to the cells.-The type I cells, identified by electron microscopy and catecholamine fluorescence, have a membrane potential of 2 - 20 mV. They are not able to generate spikes neither spontaneously nor by electrical stimulation. The intracellular posi~ tion of the electrode during the recording could be proved by staining with Procion yellow (Kaneko 1970). These results are in general agreement with experiments of Goodman (1972) and Eyzaguirre (1974). Max-Planck-Institut

fur Systemphysiologie,

D-46 Dortmund, Rheinlanddamm 201

256

VOLTAGE JUMP RELAXATION FIBRES P . Adams

OF ENDPLATE CONDUCTANCE

IN FROG MUSCLE

The voltage-jump relaxation of the endplate conductance evoked by bath-applied suberyldicholine was studied in frog muscle. Responses to suberyldicholine (20 n M - 4 ~M) were obtained in the presence of 3 ~M neostigmine, and when using high concentrations were kept sm~l by ~ -bungarotoxin pretreatment (2 X 10- g/ml for 5-10 min), whic~ did not itself detectably affect the relaxations. ~he r e l a x a t i o n time constants at 7UC and 80 ~nd 130 mV were 10.7 ~ O . 5 and 21.7 Z 1.1 msec respectively (means - S.E.; 45 responses in 22 fibres). Although these time constants showed little concentration dependence the relaxation amplitude decreased greatly in the range I - 4 ~M, In the presence of procaine the suberyldicholine relaxation showed 2 exponential components. Following a step hyperpolarisation the endplate conductance rapidly decreased then slowly increased. With an increase in procain concentration from I0 to 80 ~ M the time constant of the slow process increased about 3-fold. Abt. Neurobiologie, Max-Planck-Institut D 34 G~ttingen, Am Fassberg

fur Biophysikalische

Chemie,

R129 257 M E M B R A N E SH~GRuHPS OF I S O L A T E D A D I P O C Y T E S IN THE MEDIATION EPINEPHRINE ACTION H.Kather,M.Geiger und B.Simon

OF

Epinephrine acts via activation of adenylate cyclase. The binding of this hormone to the cell membrane as well as the catalytic actlvity of adenylate cyclase have been reported to be S H dependent (V.Tomasi et al.,Biochlm.Biophys.Acta 211,51,197o,~ye, l.,Sutherland,E.W.,Biochim.Biophys.Acta 127,347,~9-66). By using a large SH-reagent-pCMB-Dextran,MW~lo.ooowe,therefore,studied the localization of such critical SH-group@. Preloading of intact fat cells with pCMB-Dextran up to 1o .~ M did neither influence the lipolytic response to epinephrine nor the epinephrine stimulation of adenylate cyclase as determined in ghosts prepared subsequently. W h e n pCMB-Dextran, however, was present during the cell lysis , a dose-dependent inhibition of epinephrine stimulated adenylate cyclase activity was observed. These results suggest that the binding sites of epinephrine as well as SHgroups essential for activity of adenylate cyclase are not localized near enough to the exterior surface to be accessible for pCMB-Dextran. This sideness in the sensitivity of fat cell adenylate cyclase could not be observed when pCMB-Dextran was added directly to intact or fragmented ghosts suggesting that the dearrangement of membrane structure during ghost preparation exposes functionally important membrane SH-groups. Klinisches

Institut f~r Herzinfarktforschung an der Medizinischen 69 Heidelberg, Bergheimerstr. 58

Universit~tsklinlk,

258 MEMBRANE JUNCTIONS DURING EXOCYTOTIC INSULIN RELEASE FROM B-CELLS OF THE MOUSE W. Berger ,G. Dahl and H.P. Meissner

Membranes~of the secretory granules fuse with the cell membrane in the exocytotic process of insulin release from B-cells. Examination of thin-sectioned B-cells of the mouse have revealed, that pentalaminar membrane junctions are formed in the regions of membrane fusion,which resemble the image of nexus(gap junctions).Nexus are assumed to represent regions of increased m e m brane permeability. On replicas of freeze-fractured B-cells we have observed that the process of fusion induces structural alterations in the granule membranes,as membrane-associated particles accumulate in the regions of contact. Similar alterations of the membrane structure were observed in membrane junctions, which may connect adjacent secretory granules. Incubation of B-cells in hypertonic solutions revealed that membrane junctions formed during e x o c y t o s i s are indeed membrane regions with increased permeability,which functionally couple the interior of granule with the extracellular space. Structural alteration wh;ich were caused by the hypertonic solutions indicate,that the junctions have to be permeable for all solutes of the hypertonic solution,i.e, for molecules up to the size of sucrose. The observations support a hypothesis,that the formation of permeable membrane junctions may be of functional significance for the mechanism of insulin release and that the aggregation of secretory granules favours a quick release of insulin. i. Physiologisches

Institut,

665

Homburg

/ Saar

, LKH

R 130 259 DOES VOLTAGE CLAMP HYPEEPOLARIZATION DEPLETE EXTRACELLUT, AR POTASSIUM? C.M. Baumgarten Membrane current (I) elicited=by clamping to a given potential (E) is related to conductance (g) by I g(E-Erev). Since E is controlled, the assumption that Erev, the Nernst potential for the ionic species carrying the current, remains constant permits time-dependent changes in I t o be attributed to time-dependent changes in g. This assumption was tested using 2 electrode voltage clamp technique to hyperpolarize sheep PurkinJe fibers perfused with Na-free Tyrode's solution. Hyperpolarizing by 10 to 40 mV from resting potential ( R P - 8 0 mY) elicited an inward current that decreased with time. The amplitude of the time-dependent portion (id) increased with increasing hyperpolarization. Reclamping to RP elicited a declining outward current of an amplitude that increased with increased magnitude and duration of the preceeding hyperpolarization. The latter result excludes a declining inward current as the basis for i d. The time course of the envelope of 'tails' did not match the time course of i d suggesting that an increasing outward current was also not responsibIe. While an inward current was seen on clamping from RP to -95 mV, a declining outward current was seen when the potential was reclamped to -95 mV after being clamped at -105 mV for 0.5 sec. This indicates that driving force for the ionic species responsibls for was altered by clamping to -105 mV. Increasing perfusate K + from 2 to I~ mM and enlarging extracellular space by perfusion with solution made hyperosmotic by addition of 100 mM mannitol reduced i The data suggests that i d is due to depletion of extracellular ~ by hyperpolarizing current. That is, the Nernst potential for K + does not remain constant during the clamp step. II. Physiologisches Institut, Universit~t des Sa~rlandes, D665Homburg/Saar Visiting from Dept. of Pharmacology, Northwester U.o Chicago, IL USA 260 WHY IS THE PACEMAKER CURRENT ABOLISHED IN Na-FREE SOLUTIONS ? G. Isenberg When a cardiac Purkinje fiber is clamped to -100 mV, the pacemaker current iK2 deactivates totally (s=0). During depolarizing clamp steps iK2 increases with a time constant Ts from the deactivated (s=0 fo r t=0) to the partially activated state (s=soo(V) for t = ~ ) . When iK2 is totally activated by a long lasting clamp to -50 mV (s=1), it deactivates during hyperpolarization. At a given potential V the difference of the instantaneous currents (s=1 - s=0) defines the maximum conductance gK2(V), the time dependency defines the activation variable s(V,t) (Noble and Tsien, J. Physiol. 19~, 185,1968). The well known fact that in a Na-free medium iK2 disappears (Deck and Trautwein, Pfl~gers Arch. 280, 65,1964) is studied using solutions with [Na]n of 75, 50, 50, 15 and 0 raM. Three sin. after changing to [N~o =50ram the-following effects are observed: I. The steady state activatioff curve s~ (V) is shifted on the voltage axis to more negative potentials, thus iK2 is less deactivated at -85 mV. 2. The curve describing the voltage dependence of the time constant ~e(V) displays the same shift. Thus, at -85 mV the deactivation is slower. 5- The two instantaneous iv-relations (s=0 and s= I) become approached by a shift of the s=0 curve to higher outward currents. Thus, with reduced [Na]ogE2 becomes smaller, and in Na-free solutions A t disappears. The results suppQrt the hypothesis t h a t the potassium conductance is controlled by[OaZ+]i (l~?nberg, Nature, 2 ~ , 1975): At reduced [Na]o the cell can a c c u m u l a ~ Ca =* (Reuter and Seitz, J. Physiol. 19~, 451, 1968), this elevated [CaZ~imight stabilize iK2 in a state of less deactivation. II. Physiolog. Institut, HniversitRt des Saarlandes, D665 Homburg (Saar)

R 131 261 L O C A L D E V E L O P M E N T OF A C T I O N P O T E N T I A L S FIBRES H. S c h m i d t and G. S c h a l o w

IN D E N E R V A T E D

SLOW M U S C L E

Frog slow m u s c l e fibres acquire the a b i l i t y of g e n e r a t i n g a c t i o n p o t e n t i a l s after c o m p l e t e (Miledi et a l . , J . P h y s i o l . ( L o n d . ) 21_~7, 737,1971) or partial d e n e r v a t i o n (Schalow and Schmidt, N a t u r e (Lond.) 253, 122, 1975). It is, however, not k n o w n w h e t h e r the total fibre surface b e c o m e s e l e c t r i c a l l y e x c i t a b l e at the same time, or w h e t h e r some parts of the m e m b r a n e are t r a n s f o r m e d w h i l e others still have their o r i g i n a l m e m b r a n e p r o p e r t i e s . - P y r i f o r m i s m u s c l e s of R.temp. were totally or p a r t i a l l y denervated; 1-2 w e e k s later the a b i l i t y of g e n e r a t i n g a c t i o n p o t e n t i a l s was e x a m i n e d by i m p a l i n g slow fibres s u c c e s s i v e l y or s i m u l t a n e o u s l y w i t h 3-4 microelectrodes. One of these e l e c t r o d e s was used to a p p l y s t i m u l a t i n g c u r r e n t pulses; w i t h the r e m a i n i n g m i c r o e l e c t r o d e s a c t i o n p o t e n tials were r e c o r d e d at d i f f e r e n t d i s t a n c e s from the p o i n t of stimulation. In totally d e n e r v a t e d slow fibres the a c t i o n p o t e n t i a l a m p l i t u d e v a r i e d c o n s i d e r a b l y w i t h d i s t a n c e a l o n g the fibre surface. Small a c t i o n p o t e n t i a l s w i t h two peaks were o f t e n observed. In p a r t i a l l y d e n e r v a t e d fibres the results were similar. In addition it c o u l d be d e m o n s t r a t e d that the a m p l i t u d e of the end p l a t e p o t e n t i a l was i n v e r s e l y r e l a t e d to the action p o t e n t i a l amplitude. T hese results show that the a c t i o n p o t e n t i a l m e c h a n i s m (Na-channels) is b u i l t p r e f e r e n t i a l l y into some areas of the slow fibre membrane; these areas are p r e s u m a b l y identical w i t h d e n e r v a t e d end plates. D e p a r t m e n t of Physiology, Saar, G e r m a n y Supported

University

by S o n d e r f o r s c h u n g s b e r e i c h

of the Saarland, 38

665 H o m b u r g /

"Membranforschung"

262 DIFFUSION OF SUBSTRATE MOLECULES TO AN ENC~4ATIC ACTIVE SITE: AN ESTIMATION OF THE RATE CONSTANT

F. Holzer

A formula is derived for the diffusion-controlled

reaction rate between

encymes and substrates. In our model we suppose that the active site of an encyme molecule occupies a part of the surface. The moving of the substrate molecules is caused by Coulomb's-, Van der Waals'-, friction- and fluetatlon forces. For an applied electrical field we have to include tonic migration. The derived formula reflects the dependence of the rate constant from the resultant force (attraction or repulsion), from the size and structure of the encYmatic active site and the size and structure of the encyme molecule. In a more specific application we may use model interaction calculations for the molecular forces. In this way it is possible to obtain information ~bout the specific behaviour of an encyme to different substrates. In addition to that we can show a relationship between the molecular structure of some postulated "active channels" in a membrane and the membrane transport rate.

Inst. f. allg. u. exp. Pathologie, University of Vienna, A-|o9o Wien, W~hringerstra6e

13

R 132 263 INFLUENCE OF EXTRACELLULAR CALCIUM ACTIVITY ON ION DISTURBANCES FLOW ANOXIA (ISCHEMIA). J. HSper~ M. Kessler, U. Tlolka

DURING NO-

New, miniaturized, solid-state,' ion-selective surface electrodes (2, 3) enabled us to measure the kinetics of extracellular ion activity continuously during no-flow anoxia. The experiments showed that immediately after ischemia is induced characteristic ionic disturbances develop (2). We observe biphasic changes in extracellular activity of sodium and potassium. A first phase with fast flux is followed by a phase during which the flux becomes slower. This decrease in ionic flux may be caused by a n i n c r e a s e in extracellular calcium activity. Various authors (see 1) s h o w e d t h a t intracellular calcium activity has an effect on plasma membrane permeability for potassium. Recent experiments (4) give evidence that not only a decrease in calcium activity in the cytosol but also an increase in extracellular calcium activity may effect the permeability for ions. In the normal perfused rat liver, an extracellular calcium activity of 1.32 mM/l (calcium concentration 1.9 mM/l) is measured. After ischemia is induced calcium activity increases to 2.5 mM/l. This may be caused by dissociation and presumably also by an efflux of calcium. The potassium efflux which occurs during ischemia is significantly increased when the calcium is bound by EGTA before the beginning of ischemia. I) 2) 3) 4)

Blaustein. M. P., Rev. Physiol. Biochem. Pharmacol. 70, 33, (1974) H6per, J., Kessler, M., Simon, W., Urban & Schwarzenberg, in press Kessler, M., HSper, J., Simon, W., Fed. Proc. 33, 279 (1974) Kessler, M., HSper, J., Starlinger, H., Krumme, B., Urban & Schwarzenberg, in press

Max-Planck-Institut

264 THE LOCALIZATION BLOOD CELLS

f~r Systemphysiologie,

OF

CALCIUM C. Behn

D-4600 Dortmund,

IN THE MEMBRANE and A. Lfibbemeier

Rheinlanddamm

OF

HUMAN

201

RED

F r e s h e r y t h r o c y t e s o b t a i n e d f r o m c a p i l l a r y p u n c t u r e w e r e w a s h e d and s u s p e n ded i n T E S b u f f e r e d i s o t o n i c s o l u t i o n s (150 m M NaC1, pH 7.4), C h l o r o t e t r a c y c l i n e (CTC) was u s e d a s c h e l a t e p r o b e f o r m e m b r a n e b o u n d c a l c i u m i n c o n c e n t r a t i o n s r a n g i n g f r o m 0.05 to 1 m M . I n t r a c e l l u l a r f l u o r e s c e n c e d i s t r i b u t i o n was e x a m i n e d by m i c r o f l u o r o m e t r y and c e l l shape by o r d i n a r y light m i c r o s c o p y . At the e m i s s i o n m a x i m u m of the C a - C T C - c h e l a t e i n a p o l a r m e d i a (530 n m ) a d i s t i n c t f l u o r e s c e n c e w a s d e t e c t e d at the c e l l b o r d e r , In the a b s e n c e of CTC a l l c e l l s w e r e c r e n a t e d , p o s s i b l y due :to the " g l a s s effect" (R. F . F u r e h g o t t and E. P o n d e r , J . exp. B i o l . 17, 117, 1940) of the m i c r o c h a m b e r w a l l s . C r e n a t i o n i s p r e v e n t e d i n a dose d e p e n d e n t m a n n e r by CTC (no c r e n a ted c e l l s at 1 mM). C r e n a t i o n s u p p o s e d l y r e s u l t s f r o m a s u r f a c e a r e a e x c e s s of the o u t s i d e r e l a t i v e to the i n s i d e of the b i l a y e r m e m b r a n e (M. P . Sheetz a n d S. J . S i n g e r , P r o c , Nat. A cad. Sci. USA, 71,4457, 1974). P r e v e n t i o n of c r e n a t i o n b y CTC m a y b e due to i n t e r c a l a t i o n of the d r u g into the i n n e r l e a f l e t , which is c o r r e s p o n d i n g l y e x p a n d e d . D e p l e t i o n of m e m b r a n e c a l c i u m u s i n g the i o n o p h o r e A 23187 ( 2 . 7 / u g / m l ) m a d e the c r e n a t e d s h a p e m o r e r e s i s t a n t to C T C . U n d e r t h e s e coffditions the p e r c e n t a g e of c e l l s r e m a i n i n g c r e n a t e d at d o s e s above 0.1 m M C T C , w a s s i g n i f i c a n t l y h i g h e r (p ~ 0.01) t h a n c o n t r o l v a l u e s without the i o n o p h o r e . T h u s , a s s o c i a t i o n to c a l c i u m l e a d s CTC to expand the m e m b r a n e ' s i n n e r l e a f l e t . It i s h e r e w h e r e c a l c i u m a p p e a r s to be p r e f e r e n t i a l ly l o c a t e d . I n s t . f. K l i n i s c h e P h y s i o l o g i e , K l i n i k u m Steglitz d e r F U , D-1 B e r l i n 45, H i n d e n b u r g d a m m 30

R133 265 P R O C A I N E B L O C K OF S O D I U M CHANNELS DOES NOT INTERFERE W I T H BLOCK BY SAXITOXIN H.-H. W a g n e r and W. U l b r i c h t

S o d i u m currents w e r e m e a s u r e d in voltage clamp experiments on single frog nerve fibres. At e q u i l i b r i u m w i t h 1.4 nM saxitoxin (STX)othe f r a c t i o n ~y o f s o d i u m channels b l o c k e d was 0.49 • O.O02 at 16 C (• S.E.M., n S~ 8); the c o r r e s p o n d i n g effect of I mM Procaine (Proc), Yu., was O.81 • O.O1 (n = 8). W h e n 1.4 nM STX + 1 m M Proc was a p p l i e ~ the total b l o c k Y was 0.90 • 0.004 (n = 8). This value is p r e d i c t e d u n d e r the assumption that two sites exist per channel to w h i c h S T X a n d P r o c b i n d independently, one o c c u p i e d site b e i n g s u f f i c i e n t for blocking. The f o l l o w i n g relation then holds: Y = y ~ (1 --ymm) + ym| it also p r e d i c t s e.g. that after e q u i l i b r a t i o n ~ w i t h STX ~ (leading to Y = y^ ) the extra b l o c k on adding P r o c s h o u l d p r o c e e d as in the a b s e n ~ of STX (y~ = O),however s c a l e d down by a factor of (1 - y ~ ) . This was i n ~ e d observed. A f t e r t r e a t m e n t w i t h 1 m M Proc~ changing the f r e q u e n c y of (constant) test pulses f r o m i to 10 Hz led to a p a r t i a l relief of b l o c k w i t h i n about 5 p u l s e s w h i l e the b l o c k soon r e c o v e r e d on going b a c k to 1 H z . This effect was also o b s e r v e d in the STX-Proc mixture, the r e l a t i v e relief b e i n g the same as in Proc alone; no e f f e c t of p u l s e rate on sodium current was seen in STX alone or Ringer solution. Thes~ effects are i n c o m p a t i b l e w i t h the idea of a common b l o c k i n g site for STX and Proc but they fully agree w i t h the two-site model.

Dept. of Physiology, U n i v e r s i t y of Kiel, D-23 Kiel, Olshausenstr. 40 - 60 266 THE INFLUENCE O~ LOCAL ANESTHETICS ON THE FORWARD AND BACKWARD R E A C T I O N S OF THE CALCIUM PUMP OF SARCOPLASMIC RETICULUM. J. Suko, B. Scharinger, F. Winkler and G. Hellmann.

T e t r a c a i n e And n u p e r c a i n e i n h i b i t t h e p h o s p h a t e i n c o r p o r a t i o n i n t o t h e ATPase p r o t e i ~ o f s k e l e t a l m u s c l e s a r c o p l a s m i c r e t i c u l u m (SR) membranes f r o m [ 3 2 ~ - A T P a t low i o n i z e d c a l c i u m c o n c e n t r a t i o n s , by s h i f t i n g the c a l c i u m dependence of the p h o s p h o p r o t e i n f o r m a t i o n to higher calcium concentrations; t h u s t h e r a t e of c a l c i u m u p t a k e - t h e r a t e o f c a l c i u m - d e p e n d e n t ATP s p l i t t i n g and the r a t e of AT P '[ 3 2 ~ ADP p h o s p h a t e e x c h a n g e a r e r e d u c e d on a c c o u n t o f a r e d u c t i o n of t h e p h o s p h o p r o t e i n s t e a d y s t a t e l e v e l . At s a t u r ~ t i D g c a l c i u m c o n c e n t r a tions tetracaine i n c r e a s e s t h e r a t e of ATP-[32~ADP p h o s p h a t e e x c h a n g e , b u t i n h i b i t s the r a t e of c a l c i u m uptake and c a l c i u m - d e p e n d e n t ATP s p l i t t i n g , whilst the phosphoprotein formation is little affected. T e t r a c a i n e a n d n u p e r c a i n e r e d u c e t h e r a t e of A D P - i n d u c e d c a l c i u m e f f l u x f r o m c a l c i u m p r e l o a d e d SR v e s i c l e s a s w e l l a s t h e r a t e o f ATP s y n t h e s i s d r i v e n by t h e c a l c i u m e f f l u x i n d i c a t i n g t h a t b o t h d r u g s a f f e c t t h e c a l c i u m r e l e a s e m e d i a t e d by t h e ATPase p r o t e i n . T h e s e e f f e c t s seem t o be due t o a r e d u c t i o n of t h e p h o s p h o p r o t e i n formed from~2~-orthophosphate and i n t r a v e s i c u l a r c a l c i u m . On t h e o t h e r hand the A D P - i n d e p e n d e n t c a l c i u m e f f l u x i n c r e a s e s a t high drug concentrations. It is suggested that local anesthetics influence the calcium transl o c a t i o n b y t h e c a l c i u m pump o f s k e l e t a l m u s c l e SR by a f f e c t i n g t h e p h o s p h o r y l a t i o n of the c a l c i u m - t r a n s p o r t ATPase. Institute of Pharmacology, U n i v e r s i t y W K h r i n g e r s t r . 13a

of V i e n n a , 1090 V i e n n a ,

R134 267

THE EFFECT OF DMSO AND ETHYLENE GLYCOL ON SARCOPLASMIC (S.R.) MEMBRANES R. The and M.H. Stromer* Hydrophobic interactions between proteins, lipids and ATP are essential for the activity of the S.R. calcium pump (R. The and W. Hasselbach, Eur.J.Biochem.53, 105, 1975). Perturbation of these interactions by DMSO and ethylene glycol has been investigated by using three preparations of the S.R., i.e. native membranes, membranes whose phospholipids were hydrolyzed by phospholipase A and lipid-deficient membranes. Calcium-dependent ATPase activity is markedly inhibit%d by D M S O and ethylene glycol. In a low free-calcium medium (LCaCI~ = 0.8/uM), half-maximal inhibition of ATPase activity is reached at~13% DMSO (v/v) or ~20% ethylene glycol (v/v). High free-calcium concentrations ( ~ a C l ~ = !80/uM) have a protecting effect on the ethylene glycol-induced inhibition but do not protect against the DMSO-induced inhibition. Binding of ATP and extent of E~P formation by S.R. membranes in the presence of up to 65% DMSO or ethylene glycol (v/v) are not affected. In the low free-calcium medium, inhibition by either 30% DMSO or ethylene glycol on the rate of calcium u~take is identical (65-70%). In a higher free-calcium medium markedl~ ( ~ a C l ~ = 4.37/UM)phowever, the DMSO inhibition (N73%) becomes stronger than that of ethylene glycol (~55%).Membrane fusion is promoted by ethylene glycol and DMSO, but higher concentrations of DMSO (10%) destroy the bilayer structure if the fusion process is prolonged. MPI fGr med.Forschung,Abt.Physiologie, D~69 Heidelberg, Jahnstr. 29 *Dr.Stromer, Iowa State University, was a Humboldt Fellow. 268

INVESTIGATIONS ON ~ H~ODYNAMICS PLACENTA. H. -P .LeichtweiB ~H. Schr6der

O F THE ISOLATED GUINEA PIG

In the isolated, maternal and fetal artificially perfused placenta of the guinea pig the relationship between perfusionra~es and arterial and venous pressures were investigated at constant arterial perfusionrates. The results are as follows: I. Perfusionpressures in the arteries (5 - 30 mm Hg) increases directly with the perfusiourates (.6 - 6.2 ml/min). 2. Elevation of fetal venous pressure at constant arterial inflow leads to a corresponding increase of pressure in the umbilical artery. Thus the pressure drop in the fetal vessels remains at a constant level~ 5. Raising of the fetal venous pressure induces an increase of flow resistance at the maternal side, too. Fetal perfusion resistance is raised by elevated pressure in the uterine vene vice versa. 4. At high venous pressures a net transport of water caused by hydrostatic pressure differences between the fetal and aaternal side was observed. At umbilical venous pressures of 25 to 35 mm Hg the inflowing perfusion volume at the fetal artery is transferred totally to the maternal side. The results are of interest for the transport of substances ~cross the placenta. Abt. f'dr experim.Medizin der Univ.-Frauenklinik, 2 Hamburg 20, Martinistr.52

R 135

269 INFLUENCE OF ELEVATION OF VENOUS PRESSURE ON THE TRANSPORT OF 5H20,GLUCOSE AND 131 J-ALBVMINE ACROSS THE ISOLATED GUINEA PIG PLAC~TAo H. SchrSder IH.-P.LeichtweiB The effect~ of varia%ions of the flow rates and of filtration on the transfer of substances across the isolated guinea pig placenta was investigated. 1. The transfer of triti~ted water and of glucose across the placenta is flow limited in the range of flow explored ( 1.5 to 6.2 ml/min ). The observed higher concentration of 5H20 in the ~cceptor vene related to the donor vene proves an efficient countercurrent system in the guinea pig placenta. The transport of 151 J-albumine is membrane limited;it changes little with flow rates. The permeability of the guinea pig placenta ~ i s 20 x dO-3 ml/min for albumine and 4-5 ml/min for 3H20o 2. The transport of 131 J-albumine and of 3H20 resp.glucose is changed by transplacental filtration to a different degree. Whereas the albumine-transport increases strongly, the transfer rates of 3H20 and glucose changes little. Because of the countercurrent system the drop of concentration of 3H20 along the region of exchange may be very sudden, so that fluid containing low 5H20-activity is filtrated; glucose is transferred by a carrier system that is independent of filtration. The increase of albumine transfer by pressure induced filtratiom may be explained by an increase of the pore diameter Of the placental membranes. Abt.ffir experim.Medizin d e r Univers.-Frauenklinik, 2 Hamburg 20, Martinistr.52 270 PHYSIOLOGICAL AND OPERATIONAL PERFORMANCE MEASUREMENTS 0F NONPHYSICAL LOAD BY BIO-OPERATIONAL ADAPTIVE FEEDBACK. + K.-W. Mfiller, A. Adler, H. S t r a s s e r For reasons of measurements of mental load in man-machine-systems a pursuit tracking device (STRASSER, VDI-Z. 115(8)621-628,1973) has been incorporated in a process computer system. Hereby e.g. integrated absolute error, calculated from input and output of a t e s t subject when tracking different forcing functions, beat-tobeat heart rate and sinus arrhythmia (STRASSER, MOLLER and ADLER, Pflfigers Arch. 347,R24,1974) can be registered on-line by means of a digital computer. Artefact recognizing programs for the physiological parameters have been established, too. With these programs it is possible to exclude and correct distinct technical and movement artefacts in the ECG, exceeding preset tolerance levels. Moreover on the basis of on-line registered and processed test data a direct feedback allows the adaptation of the operational input (load, supported by different levels of difficulty of the tracking task) to the output of the test subject (individual performance or strain), which is indicated by operational and physiological parameters. Department of Work Physiology, Technical University of Munich, D-8000 M~nchen 40, Barbarastr.16/I, Bundesrepublik Deutschland + Supported by the Deutsche Forschungsgemeinschaft

R 186

271 ANALYSES OF THE RESPONSE OF HEART RATE AND RESPIRATION TO PHYSICAL EXERCISE H. PeSenhofer, G.Schwaberger, W.Estelherger and Th. Kenner In order to evaluate the performance of biological systems, the response to certain t e s t signals has to be examined. The goal of our study was to establish a method by which the parameters of the systems involved can be identified. Experiments were performed on 20 persons with different degrees of training, among them members of the Austrian junior cross country skiing team. During the exercise, performed on a bicycle ergometer, heart rate and respiratory variables (frequencyjventilation, oxygen consumption) were recorded continuously. The responses to short load impulses, to load steps and to pseudorandom binary sequence (PRBS) loads were tested. For the evaluation of the responses digital computer programs were developed which allow ]) to calculate the weighting function of the system from PRBS data 2) to determine the frequency response and 3) to perform a parameter identification procedure f r o m the recordings, assuming different linear models. For practical purposes, the results of these measurements and calculations were compared with the training status of the t e s t persons. The results of this comparison indicate that an application of s h o r t load impulses and PRBS loads allows to characterize the dynamic reaction of the systems. The m o s t simple models for the characterization of heart rate and ventilatory responses are second order. The advantage of our method is the possibility to express the results of a test in terms of a limited number of model parameters. Supported by the Fonds zur FSrderung der wissenschaftlichen Forschung Physiologisches Institut der Universit~t Graz, A-80]O Graz, MozartKasse 14 272

ADAPTIVE M O D I F I C A T I O N S IN THE T H E R M O R E G U L A T O R Y SYSTEM IN LONGD I S T A N C E RUNNERS. E. Baum w K. BrUck and H.P. Schwennicke Thermoregulatory responses to external cooling and h e a t l n g , u n d e r resting conditions, were recorded in 7 long-distance runners (42 km or more) and compared w i t h those in p h y s i c a l l y untrained controls. Since the runners were c o n s i d e r a b l y thinner than any ~vailable control group, each p a r a m e t e r was referred to the body 3urface/mass quotient (AD/m). All t h e r m o r e g u l a t o r y responses were more or less correlated w i t h AD/m, the resulting regression lines were s u b j e c t e d t o statistical evaluation. Sweating as well as shivering thresholds were significantly decreased in the runners when compared either in terms of mean body temperature (Tb) or esophageal temperature (Tes). Also, both T b and Ten ~ r e slightly reduced at rest under thermoneutral conditions. The runners also showed lowered mean skin temperatures (T~k) at the thresholds a n d in a thermoneutral environment, though to a lesser degree. Moreover, cold sensation in the runners occurred at lower Tb, and thermal discomfort was experienced at lower Tb in the runners, except for the thin men. The demonstrated modifications resemble, with respect to the cold defence reactions, those seen in h u m a n and animal c o l d - a d a p t a t i o n (positive cross-adaptation). As fc~the sweating threshold, the shift is q u a n t i t a t i v e l y comparable to that found in heat-adaptation. The described modifications would enable the long-distance runners to keep their body temperature at relatively l o w levels and to p r o l o n g the time period until a dangerous body temperature - o n e of the important l• factors in p h y s i c a l endurance - is reached during competition. Zentrum fur Physiologie

der Universit~t,

D 65 Giessen,

Aulweg 129

R 137 273 BLOOD GASESw LACTIC ACID CONCENTRATION AND pH DURING RECOVERY FROM STRENUOUS EXERCISE IN STANDARDBRED HORSES H.Krzywanek In standarclbred horses bloodgases, pH and lactic acid concentration were measured i n arterial as well as in mixed venous blood before and after severe exercise of short duration. Sampleswere drawn simultaneously from the carotid artery and pulmonary trunc at rest, immediately post exercise and 3t 6, 15, 30 and 60 minutes after exercise. PaO~ and pgO~ increased after exercise. The highest values were obtained 6 minutes post exercise. Restiffg values were reached after 60 minutes. PaCO2 decreased after exercise. The lowest values were found 6 minutes post exercise. P'gCO2 increased after exercise. The highest values were found immediately post exercise followed by a sharp decrease below pre-exerclse values. The lowest values were found 15 minutes post exercise. PaCO2 and pgCO 2 returned to normal withln 60 minutes. pHa values decreased sharply after exercise. The lowest values were found 6 minutes post exercise. A return towards normal occurred within 60 minutes. The lowest pHv values were measured immediately post exercise followed by a continuous rise and a return to normal within 60 minutes. Lactic acid concentration in arterial blood increased immediately post exercise. The highest values were found 6 minutes after exercise. After 60 minutes lactic acid concentration had not reached the pre-exerclse resting level.

Department of Veterinary Physiology, Free University Berlin (West), D 1 Berlin 33, Koserstral3e 20 274 INFLUENCE OF SEX AND TRAINING ON WORKING SKELETAL MUSCLE METABOLISM H. HINNE~ERG I G. GEBERT t H. RIECKERT and W.SCHNIZER Postfunct~ional blood flow and volume were measured plethysmographically in juvenile rowers and in children (age 14-15years) after strenous intermittent arm work. When exhausting arm work was repeated several times~ the time course of the postfunctional decrease in blood flow and in ~ volume became aZmost monoexponential with approximatively the same time constant. Therefore the absolute volume changes could be estimated by extrapolation of the curve. Furthermore, the peak flow - peak volume relation during reactive hyperaemia of the forearm was used to evaluate the intravascular volume changes in the postfunctional period. It was found that the changes in the extravascular volume of the forearm due to muscular work were strikingly different. Differences were observed especially between untrained and well trained probands. Additionally, differences were related to the sex of the probands. It can be assumed, that the volume changes in the extravascular compartment of the skeletal muscle de~end on osmotic gradients, which in turn are produced by intracellular increase in splitting products of anoxidative muscle metabolism. Therefore the regulation of muscle metabolism during muscular work seems to depend on the sex of the probands and might be influenced by training. Department Physi61ogie Universit~t Ulm, Oberer Eselsberg Sektion fGr Sportmedizin Universit~t Kiel,Olshausenerstra~e

R138 275

CLEARANCE FUNCTIONS INFLUENCING IMMERSION DIURESIS IN ATHLETES AND NON-ATHLETES D. BGning, W. Skipka The stimulating effect of water immersion (35,5~ on urine excretion is attenuated in athletes (BGning et al, Aerospace Med. 43, 3 0 0 - 3 0 5 , 1972). In order to clarify the underlying mechanisms--headout-immersion experiments of 4 hour duration were performed in 8 untrained (UT) and 8 endurance-trained (TR) subjects; the former results could be confirmed (maximal diuresis 3.22 + 1.60 ml/min in UT, 1.60 + 0.40 ml/min in TR; p ~ O . O 1 ) . Free water--clearance remained approximately constant in the UT but temporarily decreased by 1.17 + 0.52 ml/min in the TR ( p < O . O O 1 ) ; thus inhibition of adjuretin seemed to play only a minor role especially in the TR. Both groups showed a marked but different rise of osmolar clearance (UT up to 4.69 + 0.98 ml/min, TR up to 4.O1 + O.81 ml/min; p < O . 0 5 ) . This partly--resulted from an increase of--glomerular filtration rate (creatinine clearance) which started earlier in the UT. A second cause was a decrease of aldosterone excretion which was more pronouced in the UT ( p < O . O 1 ) . Supported by Minister for Wissenschaft und Forschung des Landes Nordrhein-Westfalen ( I I B 8 - F A 5997) Physiologisches Institut der Deutschen Sporthochschule K~in, 5 KGln 41, Carl-Diem-Weg 276 ENDOCRINE REACTIONS OF ATHLF~.~ AND NONATHLETES DURING IMMERSION W.Skipka*, D.BGning*, K.A.Deck**, K . A . M e u r e r * 4 W.R.K~Ipmann***

The different changes of orthostatic tolerance (Stegemann et al, Aviat. Space Environ.Med. 46, 26, 1975) and sodium excretion (B~ning et al, Aerospace Med. 43, 300, 1972) in trained (TR) and untrained (UT) subjects during-~atem immersion (35.5~ may depend an altered hormone production. Therefore urinary vanillylmandelic acid (VMA), aldosterone (A) and plasma renin activity were measured during immersion (4 h) in 8 UT and 3 TR males. VMA-excretion as a measure of catecholamine release showed an increase (p
R 139

277 The influence of various socks on the microclimate in shoes with u p D e r s o f leather or s~ntheticmaterial. W. Dicbschla6~V. Mauderer As formerly published, the rel.humidities (r.H.%) on an average rise to 81% r.H. in shoes made of several synthetic uppers, but only to 68%r.H. in shoes with leather during every-day life (significant difference at I% confidence level). It was the aim of these wearingtests with 8 male test-subjects (t.s.) to find Out whet~er 1.)the s-~-microclimate is influenced because of wearing various types of socks and 2.)whether a "good H sock may compensate the unphysiologic high humidity in synthetic shoes. Test-specimen: ' I n s i m i l a r lowshoes with box-calf- or synthetic-poromeric uppers the t.s. wore 8 socks at a time, manufactured of: wool, cotton, polyamide, polyacrylic, wool/polyester, cotton/polyester, wool/polyacrylic and a twolayered sock cotton/wool. Methods: With miniature thermocouples continuous measurement of the temperature gradients from the foot-skin to the shoe-inside and its outside at several points.Humidity-registration (r.H.%) between sock a n d u p p e r material. Procedure: climate chamber (22~ 40%r.H., O~15m/s): lh walking on a treadmill with 5 km/h, 2h mental work, lh lunch, 2.5h mental work, 0.5hwalking. Results: 1.)Only small, but not significant differences in skintemperatures when wearing the 8 socks and 2 types of shoes. 2.) The r.H~ differs significant at the 0.5% confidence level between the leather- and synthetic shoe, but there are only small differences between the various socks.- The diffusion-parameter (=thickness of an equivalent air layer) of leather on an average is a tenth power smaller than that of most of the synthetic uppers. It is a priority task o f i n d u s t r y to improve the diffusion of synthetic shoemat~rials. Institut f. Arbeitsphysiologie, Techn.Univers. 8 M~nchen 40, BarbarastraBe 16 278 The influence of leather- and synthetic shoe-linings on the hvmidit~ in shoes. V. Mauderer ? W. Diebschla~. Aim of investigation: Quantitative results about the influence of s h o ~ i i n i n g s on the microclimate in shoes during wearing-tests. Test-specimen: Similar low-shoes of leather or synthetic-poromeric uppers without any lining, and those shoes lined with 2 sorts of leather and 3 types of synthetic. Methods: During each test-period we measured: pulse, respiratory minute volume, metabolism, weight, rectal temperature, mean skin temperature, temperature gradients from foot-skin to the shoe outside, humidity-registration (r.H.%) between sock and shoe, heat-flux through the uppers. Procedure:In a climate chamber: 2h mental work, lh walking o n a treadmill with 5 km/h, lh mental work. The 8 male test-subjects wore a uniform summer-dress. Results: During the 2h-period the r.H. in shoes with leather uppers ( n o l l n i n g or lined with the 2 leathers) remained near the r.H. of the room climate, reached only 68%r.H. at the end of the lh-walking-period and declined quickly in the 4th testhour.In shoes With synthetic- or leather uppers, lined with the 3 synthetic materials, the r.H., caused only by insensible perspiration, increased already during the first mental work period to more than 60%r.H. ~t the end of the lh-walking the r.H. was 80-100%. Even at the end of the 4th Sest-hour a drying effect was not yet measured. These effects can be corroborated by thermodynamic calculation in regard to the diffusion-parameters of leather (5-10) and the synthetics (50~300). The fl~xes of heat and humidity through the v a r i o u s combinations of shoe-materials are calculated in relation to the experimental results. Instltut fGr Arbeitsphysiologie, Technische Universit~t MGnchen, D-80OO MGnchen 40, BarbarastraBe 16.

R 140 279 THE EFFEO"r OF TRAFFIC NOISE ON SLEEP PATTERNSOF SLEEP DISTURBED SUB3ECTS W.Ehrenstein and G.PrOfer The sleep patterns of G male e n d 6 female subjects suffering from sleep disturbances were recorded during 6 consecutive nights. Noise of a busy street traffic use presented continuously during the nights 3, 4 and 5. The noise had been tape-recorded during rush hours st m street crossing controlled by traffic lights and was presented to the sleeper by s loudspeaker inside the sleeping room. Sound pressure measurements taken near the sleeper,s head using the frequency weighting network A averaged 63 dB (range: 46 - SO dB(A)). The preliminsz~ results are taken from computer graphs, the statistical evaluation is in progress. Stage W decreased end stage REM increased from night I to night 2 (first night effect). The changes in sleep stage patterns caused by the first presentation of traffic noise during night 3 were similar to previous findingr on shift workers: increase of stsge W, reduction of stages 3, 4 and REM (W. Ehrenstein and B. Schmid in: Sleep IgTQ, Basel 1975, in press).Concarning the sleep stage patterns there usa s rapid adaptation to traffic noise, resulting in control values for stages 3 and 4 during night 4, for stsges W and REM durin 9 night 5. Outing the recovery night 6 s decrease of stage W and an increase of stage REM was observed but no chenges in the amount of stages 3 and 4. Sleep length remained constant during the test period. Institut for Arbeitsphysiologie der Technischen Universit~t MOnchen, BOO0 MDnchen 40, Berberastr.16, Germany 28O THE EFFECT OF DRUGS AND ELECTRICAL STIMULATION ON THE MECHANICAL RESPONSE OF BOVINE ARTERIES AND VEINS - H.NGUYEN-DUONG,G.GEBERT AND K.BRECHT As reported previously, helical strips of bovine facial veins responded with an intensive relaxation to electrical stimulation either by single (5-20 V;0,5-I00 msec) or by repetitive stimuli (2-5 Hz), while the corresponding arteries from the same subcutaneous region were contracting under analogous conditions (Nguyen-Duong Hoang,PflGgers Arch. 355, R 58, 1975).The relaxation of the veins is preceded by a shortlaeting contraction. This initial contraction of veins as well as the contraction of arteries cannot be suppressed by tetrodotoxin in contrast to the electrically induced venous relaxation. In some experiments on veins we observed in response to electrical stimulation initially a contraction (following the rapid transient contraction due to direct stimulation),which could be partly inhibited by tetrodotoxin or atropine.During the course of the experiment(within several h o u r s ) t h e response changed and turned gradually into the usual relaxation.These findings are paralleled by our observation that catecholamines as well as serotonin dilate the veins and contract the arteries. T h e r e l a x i n g effect in the veins decreased in the following order: serotonin, i~0proterenol, adrenaline, noradrenaline, dopamine. The relaxation by cateoholamines with the exception of dopamine was inhibited by propranolol~ The effect of dopamine could be abolished by chlorpromazine, that of serotoni~ by l~docaine. In the artery adrenaline, noradrenaline and serotoni~ (]O "J- 10- g/ml) incr@ased the tension, whereas isoproterenol (10"Og/ml) and dopamine (10"bg/ml) were ineffective.Acetylcholine (10 -8 -10 -6 g/ml)contracted the veins and relaxed the arteries;both reactions were antagonized by atropine.Our results lead to the assumption that the bovine facial vein is innervated by vasoconstrictor fibers (partly cholinergic) ana vasodilator fibers (partly adrenergiC)o Abteilung Physiology I der Universit~t 7900 Ulm, Oberer Eselsberg.

RI~ 281

A COMPUTERIZED AUTOMATICALLY SYSTEM FOR ASSESSING PROFILES OF PREPONDERANT MENTAL LOAD IN WORK STUDY INVESTIGATIONS. + W. Einars, K. Schaffle~, H. S trasser Whereas stress as the operational input of man at work may be assessed by means of time studies, work structuringinvestigat-. ions etc., strain of man at work cannot essentially be quantified without considering physiological indicators. In order to have the possibility of getting physiological profiles of working places during a complete working day, a data registering and processing system has been established. Measurements on the job - as a main demand of work studies - of heart rate (obtained from the ECG), sinus arrhythmia and electromyogram (EMG) or electrooculogram (HOG) can be registered continuously for 9 h on a portable Z-channel mag tape. The envelope curve of the rectified EMG (EMG activity) is modulated and registered in a way, which allows the same data processing as for the ECG. Both data recordings are processed by a special digital interface in connection with a digital computer in a speed, 60 times more rapid than real time recordings. By means of simultaneous registrations of a whole group of workers (minimally 4 subjects) a profile of special working places can be obtained effectively. First results of the established system are reported. Department of Work Physiology, Technical University of Munich, D-8000 MGnchen 40, Barbarastr.16/l, Bundesrepublik Deutschland + Supported by Bundesministerium fGr Arbeit und Sozialordnung 282 "OPTIMUM" VALUES IN THE LIGHT OF PHYSIOLOGY AND HUMAN ECOLOGY H. Kn~tig Architects and other "Environmental Designers" mostly aim at continuous observation of values relative to "preference" or "comfort" ("Behagli~hkeit"); this applies especially to the thermal domain (cf. FANGER, Thermal Comfort, 1973). On the other hand, medico, scientists rather consider the realization of such a constant level as a negative phenomenon ("monotony of climate"). However, there is no - or at least insufficient - evidence of concrete studies on this topic. It is for the human ecologist to pose the question as to a positive or negative evaluation of the possibility to constantly achieve the "desired" or "preferred". These parameters of motivation - asumed to be genetically fixed (cf. HERTER, Z.vgl. Physiol., 23, 605 - 650, 1936; FANGER, Thermal Comfort, 1973) evidently had been assigned positive elements of selection as long as they were serving the purpose of steering the organism into a site favourable with respect to energy balance. They may nevertheless lose their positive designation if a c o n t i n u o u s stay under such "optimum" conditions proves feasible. It need to be considered'that in this case there would be an absence of stimulation; this brings into the fore what has always been underlined by SELYE, LEVI, and others: deprivation of stimulation ("understimulation") causes "stress (SELYE)" as does an excess of stimulation ("Overstimulation") - cf. LEVI, A synopsis of ecology a ~ p s y c h i a try, 1972. Further to this, problems of human ecology proceeding beyond this are being dealt with. Biophysikalisch-Human6kologische A-1190 Vienna, Kreindlgasse 23

Forschungsstelle Wien,

R 142 283

T h e T r i a l and E r r o r J. L o e w

B e h a v i o u r of W h i t e R a t s

I n v e s t i g a t i o n s c o n c e r n i n g t h e t r i a l and e r r o r b e h a v i o u r of w h i t e r a t s in a s p e c i a l m a z e d e m o n s t r a t e d t h a t t h i s m o d e l of l e a r n i n g b e l o n g s to t h e e t h o l o g i cally well-defined conditioned appetencies, which may be characterized as f o l l o w s : a d a p t i v e and c o g n i t i v e in t h e s e n s o m o t o r i c s e c t o r and a d a m p e d a p e r i o d i c o s c i l l a t i o n f r o m t h e b i o p h y s i c a l p o i n t of v i e w . T h i s o s c i l l a t i o n f i n a l l y t u r n s into a h o m 6 o s t a t i c d y n a m i c of t h e CNS (long t e r m m e m o r y o r L T M ) . T h e s e r e s u l t s c o n f i r m s and c o m p l e t e t h e f i n d i n g s of L A S H L E Y , L O R E N Z and B E t t T A L L A N F F Y . M o r e o v e r , t h e e x p e r i m e n t s a l l o w e d to measure the learning process quantitatively and individually. The dynamics of l e a r n i n g cannot b e i n f l u e n c e d b y P u r o m y c i n a s a p r o t e i n - s y n t h e s i s i n h i b i t o r d u r i n g t h e S T M a n d L T M . A1uextinction of t h e L T M b y m e a n s of E C S , atropine, acetylcholine or other drugs as well as by long pauses between the c o n d i t i o n i n g p h a s e s in a l s o i m p o s s i b l e . If t h e r e a r e a n y c h a n g e s in t h e R N S m e t a b o l i s m , t h e s e m u s t b e p r o v o k e d b y t h e r e i n f o r c e m e n t and t h e n e g a t i v e f e e d - b a c k d u r i n g t h e I T M ( i n t e r m i t t e n d t - t e r m m e m o r y ) of l e a r n i n g . O n l y d u r i n g a v e r y s h o r t t i m e of t h e I T M , a d e t e c t a b l e t r a c e of an e n g r a m m m a y b e q u a n t i t a t i v e l y d e m o n s t r a\ b l e . I t i s p r o p o s e d to d e f i n e r a t h e r t h i s t y p e of m e m o r y b y an a d a p t i o n , i n d u c t i o n o r c o n d i t i o n i n g - m o l e c u l e . F o r s c h u n g s z e n t r u m Seibersdorf, Abteflung Biologie 2444 Seibersdorf, N. ~.

284 BRAIN TEMPERATURE

RESPONSES

TO L I G H T I N THE U N A M A E S T H E T I Z E D

C H I O K E N J. A s c h o f f and U. y o n Saint Paul As has b e e n shown in e a r l i e r publications,

brain temperature o f

the awake and s l i g h t l y r e s t r a i n e d c h i c k e n increases w h e n e v e r

light is turned on (J. Aschoff, U.v. Saint Paul: P f l ~ g e r s Arch. ~91,

109,

1968! Jap. J. Physiol.

dark cycles about

0.5~

(L:D) of 60:60 m i n duration,

b r a i n temperature

h i g h e r in L than in D. T h e s e

changes are s u p e r i m p o s e d

to a c i r c a d i a n oscillation, sites of the brain.

is

and they o c c u r s y n c h r o n o u s l y at all

S i m i l a r are the effects of short light pulses

(5 and I0 m i n duration). rature

23, 69, 1973). In r e g u l a r light-

The o b s e r v e d increases of b r a i n tempe-

are i n d e p e n d e n t of changes in a c t i v i t y as well as of food

intake. The m a g n i t u d e

of increase is a f u n c t i o n of the c i r c a d i a n

phase.

Max-Planck-lnstitut 8131Erling-AndeChs.

f~r V e r h a l t e n s p h y s i o l o g i e ,

A b t e i l u n g Aschoff,

R143 ,285 C I R C A D I A N V A R I A T I O N S OF THE E F F E C T OF L I G H T ON 0 2 - C O N S U M P T I O N IN C A R D U E L I S SPINUS. H. K l e i n Siskins were e x p o s e d to a light-regime of h o u r l y a l t e r n a t i n g light (iO0 Lux) and dark (0,O Lux). The O x y g e n - c o n s u m p t i o n and locom o t o r a c t i v i t y were recorded. The O x y g e n - c o n s u m p t i o n d u r i n g L was always h i g h e r than d u r i n g D, but the rate did not always inmaediately change w i t h i l l ~ i n a t i o n . As a r e a c t i o n to "lights on", the rate of O x y g e n - c o n s u m p t i o n alw a y s increased. This increase started i ~ e d i a t e l y after the stimulus, d u r i n g the c i r c a d i a n a c t i v i t y - t i m e ( ~ ) but showed a lat e n c y of u p to .5 hours d u r i n g r e s t i n g time ( ~ ) . The transit i o n - t i m e was always v e r y short. As a r e a c t i o n te "lights off", the rate of O x y g e n - c o n s u m p t i o n dec r e a s e d without s h e w i n g latency, but the t r a n s i t i o n - t i m e was about 40 m i n u t e s d ~ r i n g o~ and about 15 minutes d u r i n g ~ . P o s s i b l e p h y s i o l o g i c a l models for the u~iderstandin~ of these findings and similarities w i t h the so called c a r r y - e v e r p h e n o m e n a of F A I ~ R (1965) are discussed. Max-Planck-Institut

fur V e r h a l t e n s p h y s i o l e g i e ,

8131 E r l i n g - A n d e c h s

286 THE DIRECTION ASYMMETRY IN THE DURATION OF RESYNCHRONIZATION OF HUMAN CIRCADIAN RHYTHMS AFTER PHASE SHIFTS OF THE ZEITGEBEE R. Wever T i m e - s h i f t s o c c u r i n g w i t h l o n g - d i s t a n c e f l i g h t s o v e r many t i m e - z o n e s h a v e been simulated in an isolation unit, by using an artificial Zeitgeber of a strength comparable to that of the natural Zeitgeber. Eight subjects have been exposed, with exclusion of natural time cues, to an artificial 24-hr day which has been shifted twice, for six hours each into opposite d~ections, simulating first an eastward flight, and second (10 to 14 days l~ter) a westward return flight. The subjects have not been informed about the purpose of the experiments, and most of them have not even perceived consciously the Zaitgeber shifts. Results: (1) The rhythms of different physiological and psychological variables need different times: for resynchronization, i.e. to adjust to the original phase relationship tO the Zeitgeber. Thus, the results confirm once more the multi-oscillatory character of the human circadian system. (2) The duration of resynchronization is shorter after the (first) eastward shift than after the (secon~ westward shift; the amount of the direction asymmetry is different in the rhythms of different variables. This direction asymmetry found consistently in all simulation experiments is opposite to that found in most real flight experiments, and opposite to the expectation derived simply from the fact that the natural circadian period of man is generally longer than 2A hr. The hypothesis is formulated that the direction asymmetry found is due to a decrease in the rhythm's amplitude during resynchronizationo Possible causes for the discrepancy in the direction asymmetry in simulation experiments and in real flights are discussed. Max-Planck-lnstitut f~r Verhaltensphysiologie, D 8131Erling-Andechs

R 144

287 I~E S I G N I F I C A N C E OF R E T I N A L A N D E X T R A R E T I N A L P H O T O R E C E P T O R S F O R L I G H T - D E P E N D E N T CHANGES OF C I R C A D I A N R H Y T H M P A R A M E T E R S I N THE STARLING E.Gwlnner In constant light and temperature the circadian locomotor activit y r h y t h m of the E u r o p e a n s t a r l i n g ( S t u r n u s v u l g a r i s ) p e r s i s t s w i t h a p e r i o d s l i g h t l y d i f f e r e n t from 2~ h o u r s . U n d e r snch conditions b o t h the c i r c a d i a n p e r i o d ~ and the c i r c a d i a n a c t i v i t y t i m e ~ depend on light i n t e n s i t y : a n increase in light i n t e n s i t y causes a decrease in~and an increase in c~ .This effect of light intensity on ~ is a b o l i s h e d in b l i n d e d b i r d s but is not a f f e c t e d in birds i n w h i c h the i n t e n s i t y o f light r e a c h i n g the b r a i n is reduced b y s h i e l d i n g the skull w i t h b l a c k p a l n t . O n the o t h e r h a n d , t h e effect of light i n t e n s i t y on ~ i s r e d u c e d in birds treated either way. These results suggest a d i f f e r e n t i a l i n v o l v e m e n t of retinal and e x t r a r e t i n a l p h o t o r e c e p t o r s in the control of these two c i r c a d i a n r h y t h m p a r a m e t e r s : l i g h t a f f e c t i n g ~ is p e r c e i v e d p r i m a r i l y or e x c l u s i v e l y b y the eyes w h e r e a s light a f f e c t i n g ~ is p e r c e i T e d b y b o t h the eyes and e x t r a o c u l a r p h o t o r e c e p t o r s w h i c h are probably l o c a t e d in the brain. Max-Planck-Institut

fur V e r h a l t e n s p h y s i o l o g i e , 8 1 3 1 E r l i n g - A n d e c h s

288 P H O T O P E R I O D I N F L U E N C E S AGE OF PUBERTY IN THE D J U N G A R I A N H A M S T E R PHODOPUS SUNGORUS K. H o f f m a n n

I n the l a b o r a t o r y rat the age at w h i c h p u b e r t y is a t t a i n e d is s l i g h t l y i n f l u e n c e d b y the light conditions in w h i c h the animals are reared. A d e l a y of about 30 % was found in female rats kept in constant dark v e r s u s those kept in constant light| simlla~ small d i f f e r e n c e s in sexual d e v e l o p m e n t were r e p o r t e d in m a l e rats kept in d i f f e r e n t light conditions. We found a tenfold h i g h e r d e l a y in sexual m a t u r a t i o n by short p h o t o p e r l o d s in m a l e s of the D j u ~ g a r i a n hamster, a species in w h i c h adult ~ i m a l s show m a r k e d p h o t o p e r i o d i r reactions. W i t h l n 48 hours after p a r t u r i t i o n litters w e r e placed in e i t h e r l o n g (16 h light/day) or short (8 h light/day) photoperiods, and rem a i n e d in those c o n d i t i o n s until they were sacrificed at ages h e t w e e n 31 and 75 days. In long p h o t o p e r i o d s testes were fully d e v e l o p e d (average weight 850 ~ 9 m~) and caudae e p i d i d y m i d i s were full of motile s p e r m a t o z o a at the age of ~0 days. In short p h e t o p e r i o d s testes were small (average weight 89 + i0 mg) and u n d e v e l o p e d in n e a r l y all cases up to the age of 7~ days, a n d caudae e p i d i d y m i d i s c o n t a i n e d no spermatozoa. A d d i t i o n a l experim e n t s r e v e a l e d that fuil d e v e l o p m e n t of testes in short photop e r i o d s was only a t t a i n e d at the age of about 160 days, w h i c h is a d e l a y in sexual d e v e l o p m e n t of about ~00 %. It is ar~-ued that the slight influence of light conditions on sexual d e v e l o p m e n t in l a b o r a t o r y rats m i g h t be a m a r g i n a l p h o t o p e r i o d i c mechanism. Max-Planck-Inst.

f. u

D 8131 E r l i n g - A n d e c h s

R 145 289 DIURNAL VARIATION OF METABOLIC IN THE PIGEON. G. Heldmaier

AND THERMAL

RESPONSES

TO LIGHT

Pigeons w e r e k e p t

f o r t w o d a y s i n c o n s t a n t d a r k n e s s at 2 2 ~ T . E v e r y t w o h o u r s t h e y w e r e e x p o s e d to l l g h t p e r i o d s o f 20 m l n ~ u r a t i o n ( 1 1 . 3 L u x ) . 0 2 - c o n s u m p t i o n as w e l l as b r a i n , m u s c l e , and skin temperature were recorded continuously. During each light period the pigeon responded withoan increase in 02-consumption and b o d y t e m p e r a t u r e s ( + 0 . 5 +1.9 C). M a x i m u m 0 ~ - c o n s u m p t i o n a n d t e m p e r a t u r e s w e r e u s u a l l y r e a c h e d w i t h i n 10 m I B . F o l l o w i n g l i g h t o f f the 0 _ - o o n s u m p t l o n and body t e m p e r a t u r e s r e t u r n e d s l o w l y t o t h e i r o r i g i n a l l e v e l w i t h i n 30 to 60 m i n . T h e i n t e n s i t y of the m e t a b o l l c r e s p o n s e to l i g h t s h o w e d a d i u r n a l v a r i a t i o n w i t h m i n i m u m v a l u e s d u r i n g the n i g h t (+20 ~) a n d a d i s t i n c t m a x i m u m at 1 6 . 0 0 (+86~). T h i s m a x i m u m was not correlated w i t h the d a i l y m a x i m u m o f 0 . - c o n s u m p t i o n and body temperature ( 1 2 o 0 0 ) b u t o c c u r r e d d u r i n g ~ t h e descending phase of t h e i r d i u r n a l r h y t h m . A s i m i l a r d i u r n a l v a r i a t i o n o f metabolic responses w a s obtained w h e n l i g h t w a s a p p l i e d d i r e c t l y to the brain via small l l g h t - e m i t t i n g d i o d e s i m p l a n t e d i n t o the s k u l l . Max-Planek-Institut Andeehs

f~r Verhaltensphyslologie,

D 8 1 3 1 Erling-

290 THE "Po2-OPTODE" , A NEW TOOL TO MEASURE Pc 2 OF BIOLOGICAL GASES AND FLUIDS BY QUANTITATIVE FLUORESCENCE PHOTOMETRY. D.-W. LClbbers and N. OpitZ Vaughan and Weber have shown the fluorescence quenching of pyrenebutyric acid by oxygen by measuring the lifetime or the relative yield of fluorescence. Knopp and Long]muir applied this reaction for intracellular measurement of oxygen concentration. Consequently we have tried to develop a new method to measure Po^ by quantitative fluorescence photometry The fluorescence spectra are measured wlth the spectrofluorometer deve89 by Boldt and L~bbers. In a special device, the so-called "optode", a iO M solution of pyrenebutyric acid in dimethylformamid forms a IO/um thick layer, which is separated from the medium to be measured by a membrane. ~ e other side o f the layer is covered by a quartz window and used for optical measurements. With this set up we avoid concentration changes of the indicator and interactions of the indicator with other substances. In a reciprocal plot of the fluorescence intensity S' versus Po2, we obtain a linear calibration curve from O - 300 torr, i. e. Stern-Volmer-quenching. Using a 6/um teflon membrane the response time was 2 - 3 s (90 % of final value). Thi~ method has the advantage that in contrary to the Pt-electrode the reaction with pyrenebutyric acid does not continuously consume oxygen. The same principle qan be used to measure other substances, such as Pco 2 with the indicator B-methylumbelliferon, as already published ~I). We are also developing a method for measuring Po 2 and Pco^ simultaneously by using indicator mixtures or two z optodes connected in series or parallel. (1) Opitz, N., and D. W. L~bbers~ PflQgers Arch. 355, Suppl. No. 240

(1975), p. R 120,

Max-Plar~ck-~nstitut far Systemphysiologie, D-4600 Dortmund, Rheinlanddamm 201

R 146 291 A PO^ GASELECTRODE WITH 95 % RESPONSE TIMI~S OF 7 TO 10 MS K. Di~ther and W. K.R. Barnikol A clark- type electrode had been developed for continuous measurement of oxygen tension in the gas phase (D(~HRING, DIEFENTH~,LER,BARNIKOL, Oxygen Supply, 1973, p.86 91, MUnchen ). A polytetrafluoroethylene membrane ( PTFE ) had been used as membrane material with a thickness in the range of 0.2 to 1.0 F. Under optimal experimental conditions it was possible to achieve 95% response times of about 20 ms with the aid of this membrane. It became necessary that these response times could be achieved in routine. For this the production of the membrane and the POo electrode were modified. The PTFE- fluorocarbon dispersion (type 30-N, Du Pont de I
(flow/area)

can be measured by generating electrochemically

o n e e l e c t r o d e a n d measuring polarographically the local h y d r o g e n pressure with a s e c o n d o n e (D. W. L0bbers, K. St0sseck, Naturwissenschaften 57~ hydrogenwith

311 (1970)). We found a new simple quantitative evaluation to calibrate the continuous flow measurements. The pH 2 amplitude S(t o) at the time t o a n d t h e area

L = I t

S(ti dt

below the decreasing pH 2 curve a r e m e a s u r e d .

(At t h e

o

t i m e t we stopp the hydrogen generation.) The flow per area v can be calculated b y the~ rather simple equation: ~ = r S(t )/L (r = distance between o . . o

the electrodes), with the normal probe we needed several callbratlon polnts the total flow range, furthermore the calibration c u r v e d e p e n d e d o n t h e flow direction. To overcome this difficulties we constructed a new flow probe consisting of a ring shaped electrode to generate and another electrode in the center of the ring to measure hydrogen. The measurements with this flow probe is independent of the flow direction and especially suited for the continuous measurements. For measuring the microflow in the beating h e a r t t h e flow probe w a s g l u e d o n t h e heart surface by Histacryl. The heart m o v e m e n t s m a d e it necessary to use of an electrical low pass filter. T h e t h e o r e t i c a l calculation showed that the correct flow values can be obtained using a simple correction term for the filter effect. over

Max-Planck-Institut far Systemphysiologie,

D-4600 D o r t m u n d ,

Rheinlanddamm

201

R 147 293

DETERMINATION OF REGIONAL HEAT PRODUCTION AND REGIONAL BLOOD FLOW IN DOG MYOCARDIUM. H. Bending, W. Mfiller-Schauenburg and E. Betz t

"

'

Regional heat production (RHP) and regional blood flow (RBF) were determined in the myocardium of anaesthetized dogs in order to comprehend regional disturbances of tissue metabolism (e.g. during experimental coronary occlusion). - Locally produced heat leaves the myocardial tissue both'by heat convection (by blood flow) and by diffusion (conduction). The convective portion was ascertained w i t h t h e a i d o f RBF and a mean d i f f e r e n c e b e t w e e n t i s s u e t e m p e r a t u r e and a r t e r i a l t e m p e r a t u r e ( i n p u t t e m p e r a t u r e ) . An e s t i m a t i o n o f h e a t d i s p e r s i o n by d i f f u s i o n t o t h e e n d o - and e p i c a r d i a l s u r face requires certain assumptions about the shape of the temperat u r e f i e l d . - Two t o f o u r t h e r m i s t o r s , implanted into different r e g i o n s of the myocardium, w e r e employed f o r the i n t e r m i t t e n t det e r m i n a t i o n o f b o t h RBF and t i s s u e t e m p e r a t u r e i n e a c h o f t h e s e r e g i o n s . An a d d i t i o n a l t h e r m i s t o r was p l a c e d i n t h e lumen o f t h e a o r t a t o m e a s u r e i n p u t t e m p e r a t u r e . - We r e c o r d e d : 1) h e a t i n g o r c o o l i n g c u r v e s f o r d e t e r m i n a t i o n o f RBF ( i n t e r m i t t e n t heating of one t i s s u e t h e r m i s t o r ; s e e h e a t c l e a r a n c e m e t h o d , M f i l l e r - S c h a u e n b u r g , W., I n a u g . D i s s . , T f i b i n g e n 1 9 7 2 ) ; 2) t i s s u e t e m p e r a t u r e (same t h e r m i s t o r w i t h o u t h e a t i n g ) ; 3) t e m p e r a t u r e o f t h e a r t e r i a l b l o o d ; 4) c o n t r o l p a r a m e t e r s : a r t e r i a l blood pressure, heart rate and ECG. - The v a l u e s o f RHP and o f t o t a l m y o c a r d i a l h e a t p r o d u c t i o n ( c a l c u l a t e d from m y o c a r d i a l 02 d i f f e r e n c e and RBF) were comparable under varying experimental conditions, e.g. during hypoxaemic hypoxia or during infusion of dipyridamole. P h y s i o l . I n s t . I and N u c l e a r m e d . D e p t . o f R a d i o l . Universit~t, D 74 Tfibingen, Gmelinstr. S

Inst.,

294 9 HE DYNAMIC BEHAVIOUR OF CO2 - AND 02-ELEC~RODES IN STRRAMINGPLUIDS

A. Lut~aann and K. l ~ c k e n h c f f The t r a n s i e n t r e s p o n s e of 002- and 0 2 - e l e c t r o d e s i n f l u i d s i s s t u d i e d a t various flow velocities and various mountings. For this aim two solutions containing different gas partial pressures and different dye c o n c e n t r a t i o n s p a s s a l o n g the e l e c t r o d e . The time course of thepartial pressure in the measuring chamber is ,determined a) by a photometric method with the help of the dye dilution curve, b) by direct measurement of pCO 2 and p0 2 with recently developed electrodes the transient time of which has been decreased by a f r e q u e n c y - r e s p o n s e e q u a l i z & t i o n n e t w o r k . The d i f f e r e n t time c o u r s e s of both s i g n a l s a l l o w to determine the t r a n s m i s s i o n c h a r a c t e r i s t i c hydrodynamio~oundax7 layer.

of t h e

By comparison of the experimental data with%he results of the theory based on theoretical considerations of Schuler and Ereuzer (Respiration Physiology~, 90-110, 1967) and Crank (Oxford 1967) error functions in dependence o f the flow v e l o c i t i e s a r e d e t e r m i n e d . I n s t . f . P h y s i o l o g i e . Leh~stuhl I , R u h r - U n i v e r s i t ~ t Bochum, 4630 Bochum

R t48 295 METHODOLOGY "OF A pH NEEDLE ELECTRODE.

M. Kessler, B. B611ing

A new and relatively simple method was developed for the production of pH needle electrodes with a pH-sensitive length of iOO/u: about one half of a capillary of pH-sensitive glass (type O150, C o m i n g ) is coated with a glaze (TR-514 A, Pemco, Division of Glidden Co., Baltimore). The glaze is fused to the capillary by heating at 600 ~ (Carter et al., Fed. Proc. 26, 1322 (1967). Then the capillary is drawn with an electromagnetic puller so that a tip diameter of I - 2/u and a length of the uncovered pHsensitive glass of approximately lOO/u results. The tip of the electrode is sealed with a microforge and then th~ electrode is filled with 0.i M HCl under vacuum. Finally, a Ag/AgCI wire is inserted into the electrode. Measurements are performed with electrometer amplifiers and a Ag/AgCl reference electrode. The electrode gives a'stable and linear calibration curve w i t ~ a slope of 55 - 58 mV at 25 C. The impedance of the electrode amounts to iO ohms. Max-Planck-Institut far Sys~emphysiologie, D-4600 Dortmund, Rheinlanddamm 201

296 MICROELECTRODES F O R M E A S U R I N G L O C A L H + - A C T I V I T Y IN T H E S U B A R A C H N O I D S P A C E OF CATS. W. S c h n e i d e r , W. K u s c h i n s k y , M. W a h l a n d K . T h u r a u

CORTICAL

In a p r e v i o u s s t u d y ( K u s c h i n s k y et al., C i r c . R e s . 31, 24o, 1972) an i n v e r s e c o r r e l a t i o n b e t w e e n t h e c h a n g e s in p i a l a r t e r i a l d i a meter and the HCO~-concentrations of t h ~ p e r i v a s c u l a r l y ~njected m o c k s p i n a l f l u i d w a s v e r i f i e d . For a q u a n t i f i c a t i o n of t h e p H d e p e n d e n c y of p i a l a r t e r i a l r e s i s t a n c e u n d e r d i f f e r e n t e x p e r i m e n t a l c o n d i t i o n s the d i r e c t l o c a l m e a s u r e m e n t of H + - a c t i v i t y m u s t be p e r f o r m e d at t h e v e s s e l wall. S p e a r t y p e p H - m i c r o e l e c t r o d e s (Hinke-type) w e r e c o n s t r u c t e d w i t h a s e n s i t i v e t i p of 20 to 3o /u l e n g t h and 1o to 15 / u d i a m e t e r . T h e full pH r e s p o n s e w a s a c h i e g e d In I to 1o s e c o n d s . T h e c a l i b r a t i o n c u r v e s w e r e l i n e a r (range p H I to 9), t h e s e n s i t i v i t y at 37 ~ C w a s 61 to 62 m V / p H . T h e r e f e r e n c e electrode was a micropipette (tip d i a m e t e r : 2/u), f i l l e d w i t h 15o m M KC1. T h e e l e c t r o d e s w e r e c o n n e c t e d w i t h a d i f f e r e n t i a l a m p l i f i e r ( K e i t h l e y 6o4, i n p u t r e s i s t a n c e lo 14 ). - T h e i n - v i v o a p p l i c a t i o n of t h e s e e l e c t r o d e s i n s e r t e d in t h e c o r t i c a l suba r a c h n o i d s p a c e w a s t e s t e d by c h a n g i n g t h e a r t e r i a l p C O 2. For an in-vivo calibration mock spinal fluids with varying pH-values were microinjected i n t o t h e c o r t i c a l s u b a r a c h n o i d s p a c e in t h e i m m e d i a te v i c i n i t y of the p H - e l e c t r o d e s . D e p a r t m e n t of P h y s i o l o g y , Pettenkoferstr. 12

University

of M u n i c h ,

8 Munich

2,

R149

297 CONTINOUS MEASUREMENT GLASS-MICROELECTRODES

OF C E L L - M E M B R A N E - C O N D U C T I V I T Y M . S c h i e b e and P.Pauschinger

WITHSINGLE

Cell conductivity measurements have been routinely accomplished w i t h two s i n g l e g l a s s - m i c r o e l e c t r o d e s or one d o u b l e b a r r e l e l e c t r o d e b u t h a v e b e e n r e s t r i c t e d to c o m p a r a t i v e l y large cells. S e v e r a l a p p r o a c h e s to fit the n e e d of i m p a l i n g a s m a l l cell w i t h b u t a s i n g l e e l e c t r o d e came out n o t to b e s a t i s f a c t o r y . They could g i v e o n l y an e s t i m a t e of cell p r o p e r t i e s , s i n c e m i c r o e l e c t r o d e imp e d a n c e c o u l d n o t be k e p t c o n s t a n t d u r i n g i m p a l e m e n t ( O . S c h a n n e , e t al.,J.Gen.Physiol.49,897,1966). A polarisation with a current pulse t r a i n has b e e n s u g g e s t e d by R . B r e n n e c k e and B . L i n d e m a n n (T.I.T.J. L i f e S c i . , ! , 5 3 , 1 9 7 1 ) to take a d v a n t a g e of the m i n o r m i c r o e l e c t r o d e t i m e c o n s t a n t c o m p a r e d w i t h the time c o n s t a n t of the cell m e m b r a n e . In o r d e r to e n s u r e s i m p l e f i l t e r i n g c o n d i t i o n s for a n a l o g long t e r m m e a s u r e m e n t we are i m p o s i n g two c o n s e c u t i v e c u r r e n t p u l s e s w i t h a p u l s e - w i d t h r a t i o of at least I : 50 t h a t are c h o s e n a c c o r d i n g to the a p p r o p r i a t e m e m b r a n e and e l e c t r o d e time c o n s t a n t s . P e a k d e t e c tors are u s e d to d i s p l a y the d a t a . T h e r e ist no n e e d of b a l a n c i n g a b r i d g e . A f t e r a n a l o g s u b t r a c t i o n all p a r a m e t e r s are p r e s e n t e d s e p a r a t e l y t o g e t h e r w i t h the m e m b r a n e p o t e n t i a l , t h a t ist s a m p e l e d in the c u r r e n t - f r e e i n t e r v a l s . T h u s m e m b r a n e c o n d u c t i v i t y , t h a t is a l s o a v e r y s e n s i b l e i n d i c a t o r for a g o o d cell i m p a l e m e n t , e l e c t r o d e i m p e d a n c e , t h a t can be u s e d for the e s t i m a t i o n of cytoplas-m a t i c r e s t i v i t y and m e m b r a n e p o t e n t i a l can be r e p r e s e n t e d e q u a l l y . Department

of P h y s i o l o g e ,

University

of Ulm,

D 79 U l m

ACTIVITY MEASUREMENTS WITH ANEW CALCIUMION-SELECTIVE OF 4 - 6. R. Strehlau, J. H6per, and M. K e s s l e r

ELECTRODE

298 WITHIN A pCa

Activity measurements in aqueous solutions of calcium ions with new calcium electrodes (M. Kessler, J. H6per, and K. H~jek, Pfl~gers Arch. Suppl. 355, R 122 (1975), M. Kessler, K. H~jek, and W. Simon, Urban & Schwarzenberg, in press) show a linear relationship up to a pCa of 4. Within a pCa range of 4 - 6 the electrode gives a non-llnear calibration curve with a decreasing slope at'increasing pCa values. In order to perform meastlrements within this low range of activity we approximated the non-linear calibration curve with a mathematical function, which was calculated with a computer. For this procedure of approximation at least 5 calibratienpoints are needed. For preparing the solution very pure de-ionized water is used. Its quality is controlled by atomic-absorptionspectr~photometry. The interference of other ions was also investigated. The results emphasize the importance of such selectivity measurements when ion activity is monitored by means of ion-selective electrodes within a high range of pCa. Max-Planck-Institut f~r Systemphysiologie, D-4600 Dortmund, Rheinlanddamm 201

R 150

299 I M P R O V E M E N T OF C O M P A R T M E N T A N A L Y S I S BY S T A T I S T I C A L M E T H O D S M, Skalicky and J.Leibetseder r

The t h e o r ~ and application of compartmental analysis can be considered in terms of three main problems, i) The development of a p l a u s i b l e model for any p a r t i c u l a r biological systems. 2) The p r o b l e m of developing the analytic t h e o r ~ for such a system. 3) What data should be c o l l e c t e d c a n d how does one use the data to obtain estimates of the m o d e l p a r a m e t e r s and how does one decide w h i c h model is the "best". As an example the trace element m e t a b o l i s m was selected. For d i s c r i b i n g the kinetic p r o c e s s o f trace element m e t a b o l i s m the m a m m i l l a r y model seemed be most adequat. From the experimental data of the spec. activity of the trace element in the blood p l a s m a after simple i.v. injection the number and size of compartments and the transfer rates were calculated. The number of compartments was not p o s t u l a t e d b y the model, but it was decided by a statistical m e t h o d reported in detail.

Institut f~r Physiologie, T i e r ~ r z t l i c h e H o c h s c h u l e Wien, Linke B a h n g a s s e ii, A - 1 0 3 0 W I E N This study was suppoted by the Fonds zur FSrderung der wissenschaftlichen Forschung. 3OO COMPUTER-ASSISTED EVALUATION OF CARDIOTACHOGP~MS DURING EXERCISE E.W~rz +, M.Nagel, E.Epple Examples are given to show several possibilities for the record and off-line computer evaluation of cardiotachograms ~ during exercise.

Regression curves are given to allow a fundamental

interpretation of the tachogram during work and recovery. A good approximation is possible by the empirial function y - ax b e cx. Quantitative interpretations

can be accomplished

by further examination of th~ appropriate data. Digital filtering is used in order to display data due to short time changes of the tachogramm

(e.g. by respiratory arrhythmia)

and due to time-shifts of single pulse intervals. tion of non-important frequency-components gram is possible.

Statistical parameters

Thus elimina-

of the cardiotacho-

are considered for

further evaluation. Institut f~r Biomedizinische Technik an der Universit~t Stuttgart + present address: Department Physiologie, D 79 Ulm, Postfach 40 66.

Universit~t Ulm,

R 151 301

AN ATTEMPT TO ADEPT AUTHORITATIVE MEDICAL DOCUMENTATIONTO ELEC-

TRONIC ANALYTICAL TECHNIQUE/EAT/ON THE EXAMPLE OF A SCHEME OF A N~CROPSY RECORD. NiepoZomski W., Ma#ewski H.., B i e l o w s k i P. C i o l k o s z I . D e p a r t m e n t o f P a t h o l o g y , S i l e s i a n M e d i c a l Academy, K a t o w i c e , P o l a n d The a u t h o r s have worked o u t a scheme o f a n e c r o p s y r e c o r d a d a p t e d t o e l e c t r o n i c a n a l y t i c a l t e c h n i q u e . While programming t h e scheme t h e following p r o b l e m s were s o l v e d : 1 / d e t e r m i n a t i o n o f i d e n t i c a l e n t r i e s and a r r a n g i n g them i n t o main and s u b o r d i n a t e s e r i e s , 2/determination of a code for the entries of the main groups and subgroups, 3/graphic elaboration of proper inserts for a modified necropsy record, 4~elaboration of a proper instruction how to fill in the record, and 5/elaboration of a proper control system. According to the authors it will be necessary to train employees of a given institution before new documentation is introduced. It may happen that during tentative application of the record it will be necessary to make some correction of even modify the suggested documentation. The introduction of a modified and programmed medical document all over the country is very useful. The authors payed attention to the causes and conditions which made present data processing and application impossible.

Department of Pathology, S ~ e s i a n M e ~ c a l A c a d e m y , K a t o w i e e , , Poland 302 TACHISTOPHONICS - A NEW TECHNIQUE THRESHOLDS IN H E A R I N G K. Eckel

FOR EVALUATION

OF TIME

T h e i n f o r m a t i o n g i v e n by a u d i o m e t r i c w o r d s is r e d u c e d by m e a n s o f p u t t i n g a n a c o u s t i c e l e c t r o n s w i t c h b e t w e e n a t a p e b e a r i n g the t e s t w o r d s o r s e n t e n c e s a n d the e a r p h o n e s . T h e s o u n d i m p u l s e s a r e s h o r t e n e d d o w n to 3 ms. T h e i n t e r v a l s b e t w e e n t w o s o u n d i m p u l s e s w e r e s e t s e p a r a t e l y a n d i n d e p e n d e n t , e i t h e r e q u a l o r l o n g e r t h a n the s o u n d d u r a t i o n . In c a s e of dichotic stimulation offering sound impulses both ears alternating~ repre= s e n t i n g b i n a u r a l t a c h i s t o p h o n i c s , the u n d e r s t a n d i n g of w o r d s is r e t a i n e d up to c h a n g e - f r e q u e n c i e s as h i g h as 1.50 Hz. U n d e r c o n d i t i o n s of m o n a u r a l t a c h i s t o p h o n i c s the i m p u l s / / i n t e r v a l r a t i o r e a c h e s the l i m i t of u n d e r s t a n d i b i = l i t y a t 1//7 a s l o n g as the d u r a t i o n of one p h a s e s t a y s w i t h i n a r a n g e of 15 to 40 ms. W i t h i n t h i s r a n g e w o r d s a r e u n d e r s t o o d a l t h o u g h the sum o f i m p u l s e s is o n l y 125 ms. L o w e r i n g the f r e q u e n c y o f p h a s e s b y l o n g e r i m p u l s e s a n d i n t e r v a l s - the r a t i o b e i n g co,,~stantly 1//7 - d o w n to a b o u t 18 to 16 H z m a k e s u n d e r s t a n d i n g o f t e s t w o r d s i m p o s s i b l e . T h e s e f r e q u e n c i e s a p e s u p p o s e d to be the m a n i f e s t a t i o n of a t i m e t h r e s h o l d in the h e a r i n g p r o c e s s l i m i t i n g the p e r c e p t i o n of i n f o r m a t i o n b y s p e e c h . D e p t . of P s y c h o l o g y ,

Phyiology Unit,

University

of S a l z b u r g ,

A-5020