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Intracellular distribution of doubly labelled creatine phosphate in therabbit myocardium
70 190 CHANGES IN PURINE METABOLISM WITH TIME AFTER LAD-OCCLUSION IN DOG HEARTS IN SITU AND THE eFFECT OF MIOFLAZINE, A NUCLEOSIDE TRANSPORT INHIBITOR. H. Van Belle, R. Xhonneux, W. Flameng". Janssen Pharmaceutlca, B-2340 Beerse, Belgium and *Department of Cardiovascular Surgery, University Clinic St. Rapha~l, B-3000 Leuven, Belgium Needle biopsies were taken at time intervals ranging between O.5 and 6~ min after LAD occlusion in open chest control dogs (n = 9) and anlmals pretreated orally with mioflazine at 2.5 mpk (n = 7) and analysed for CrP (luminometry), Pi (spectrophotometry) and the nucleotides, nucleosides and purine bases (HPLC). In control animals, CrP dropped by 50 % and Pi almost doubled within 0.5 min. ATP slightly decreases during 8 min followed by a rapid fall to 30 ~ at 64 min. ADP and AMP rise within 1 min by 38 ~ respectively 48 %. ADP then shows a plateau at 4 to 8 min and then decreases again. AMP continues to rise to up to I0 ~ of the total purines at 64 min. Ado and Ino formation starts at 4 min reaching a maxlmum at 16 min for Ado (5.5 ~ of total purines) which further declines whereas Ino rises to almost 50 os the total purlnes at 64 min. Treatment wlth mioflazine shows a very significant effect on the AdolIno ratio over the whole period of nucleoside fo~nnatlon, being around I0 times the ratio in the controls.
191 INTRACELLULAR DISTRIBUTION OF DOUBLY LABELLED CREATINE PHOSPHATE IN T H E RABBIT MYOCARDIUM. A.Breccia~A.Fini,S.Girotti,E.Gattavecchia. lstituto di 5cienze Chimiche,Facolt& di Farmacia~Universit& di Bologna~Italy Given the fact that Creatine P h o s p h a t e (CP) h a s a p r o t e c t i v e a c t i o n on the myocardium~the q u e s t i o n p o s e d is w h e t h e r t h i s p o l a r m o l e c u l e m a y c r o s s t h e 14 c e l l m e m b r a n e . U p t a k e of C-Creatine 32p-Phosphate by rabbit m y o c a r d i u m was e x a m i n e d in v i t r o a n d in v i v o . T h e r e was s i g n i f i c a n t myocardial u p t a k e of 14C4and/ 32p - l a b e l s . T h e r a t i o 14C:32p ( 4 0 : 6 0 ) w a s u n c h a n g e d on c e l l u l a r u p t a k e . The C a n d 32p _ l a b e l s w e r e p r e d o m i n a n t l y (85% in v i t r o a n d 50~0 in v i v o ) a s s o c i a t e d within the mitochondria a n d h o m o g e n i z a t i o n of t h e m i t o c h o n d r i a l fraction resulted in s o l u b i l i z a t i o n of t h e r a d i o a c t i v i t y . TLC a n a l y s i s c o n f i r m e d t h a t t h e 14C a n d 32p labels comigrated predominantly w i t h C P . T h e r e s u l t s i m p l y t h a t CP m a y c r o s s t h e cell (and mitochondial ?) m e m b r a n e . T h i s u p t a k e m a y be e n e r g y - d e p e n d e n t or may d e p e n d on m e m b r a n e i n t e g r i t y in t h a t m i t o c h o n d r i a l "in vitro" loading decreased in a n o x i a .
192
EFFECTS OF D L - C A R N I T INE, D L - A C E T Y L C A R N I T I N E ~ AND L - P R O P I O N I L C A R N I T I N E ON HAE I M O D I N A M I C FUNCTION OF ISOLATED R A B B I T HEARTS. M . C . B i g o l i , R. F e r r a r i ~ R. R a d d i n o ~ C. C e c c o n i , O. V i s i o l i a n d A . A l b e r t i n i . * C h a i r o f C a r d i o l o g y and *lnsti t u t e of C h e m i s t r y , University of B r e s c i a , Italy. The e f f e c t s of D L - C a r n i t i n e ~ DL-Acetylcarnitine and L-Propionilcarnitine on myocardial contractility and coronary resistance were evaluated in p e r f u s e d h e a r ts. Heart contractility w a s m e a s u r e d b y m e a n s of l e f t p r e s s u r e r e c o r d i n g and cor o n a r y resistances by m e a n s of perfusion pressure recording, c o r o n a r y flow being constant. A l l t h e s u b s t a n c e s i n d u c e d a dose r e s p o n s e d e p e n d e n t c o r o n a r y v a s o d i latation ( f r o m 10 - 4 M o n ) . The o r d e r of p o t e n c y w a s : D L - A c e t y l c a r n i t i n e , DL-Carnitine~ L-Propionilcarnitine, DL-Acetylcarnitine b e i n g 10 t i m e s more p o t e n t t h e n DL-carnetine a n d 100 t i m e s more p o t e n t t h e n L - P r o p i o n i l c a r n i t i n e . T h i s e f f e c t is not related to an adrenergic or cholinergic m e c h a n i s m . DL-Acetylcarnetine present also a positive inotropic effect u n d e p e n d e n t of cardiac B-adrenergic stimulation~ whilst L-Propionilcarnitine h a d a dose d e p e n d e n t negative inotropic effect at a dose between 10-3 M a n d 10 -2 M. W h e n administred at lower d o s a g e L-Propionilcar nitine did not altered cardiac contractility.
191 INTRACELLULAR DISTRIBUTION OF DOUBLY LABELLED CREATINE PHOSPHATE IN T H E RABBIT MYOCARDIUM. A.Breccia~A.Fini,S.Girotti,E.Gattavecchia. lstituto di 5cienze Chimiche,Facolt& di Farmacia~Universit& di Bologna~Italy Given the fact that Creatine P h o s p h a t e (CP) h a s a p r o t e c t i v e a c t i o n on the myocardium~the q u e s t i o n p o s e d is w h e t h e r t h i s p o l a r m o l e c u l e m a y c r o s s t h e 14 c e l l m e m b r a n e . U p t a k e of C-Creatine 32p-Phosphate by rabbit m y o c a r d i u m was e x a m i n e d in v i t r o a n d in v i v o . T h e r e was s i g n i f i c a n t myocardial u p t a k e of 14C4and/ 32p - l a b e l s . T h e r a t i o 14C:32p ( 4 0 : 6 0 ) w a s u n c h a n g e d on c e l l u l a r u p t a k e . The C a n d 32p _ l a b e l s w e r e p r e d o m i n a n t l y (85% in v i t r o a n d 50~0 in v i v o ) a s s o c i a t e d within the mitochondria a n d h o m o g e n i z a t i o n of t h e m i t o c h o n d r i a l fraction resulted in s o l u b i l i z a t i o n of t h e r a d i o a c t i v i t y . TLC a n a l y s i s c o n f i r m e d t h a t t h e 14C a n d 32p labels comigrated predominantly w i t h C P . T h e r e s u l t s i m p l y t h a t CP m a y c r o s s t h e cell (and mitochondial ?) m e m b r a n e . T h i s u p t a k e m a y be e n e r g y - d e p e n d e n t or may d e p e n d on m e m b r a n e i n t e g r i t y in t h a t m i t o c h o n d r i a l "in vitro" loading decreased in a n o x i a .
192
EFFECTS OF D L - C A R N I T INE, D L - A C E T Y L C A R N I T I N E ~ AND L - P R O P I O N I L C A R N I T I N E ON HAE I M O D I N A M I C FUNCTION OF ISOLATED R A B B I T HEARTS. M . C . B i g o l i , R. F e r r a r i ~ R. R a d d i n o ~ C. C e c c o n i , O. V i s i o l i a n d A . A l b e r t i n i . * C h a i r o f C a r d i o l o g y and *lnsti t u t e of C h e m i s t r y , University of B r e s c i a , Italy. The e f f e c t s of D L - C a r n i t i n e ~ DL-Acetylcarnitine and L-Propionilcarnitine on myocardial contractility and coronary resistance were evaluated in p e r f u s e d h e a r ts. Heart contractility w a s m e a s u r e d b y m e a n s of l e f t p r e s s u r e r e c o r d i n g and cor o n a r y resistances by m e a n s of perfusion pressure recording, c o r o n a r y flow being constant. A l l t h e s u b s t a n c e s i n d u c e d a dose r e s p o n s e d e p e n d e n t c o r o n a r y v a s o d i latation ( f r o m 10 - 4 M o n ) . The o r d e r of p o t e n c y w a s : D L - A c e t y l c a r n i t i n e , DL-Carnitine~ L-Propionilcarnitine, DL-Acetylcarnitine b e i n g 10 t i m e s more p o t e n t t h e n DL-carnetine a n d 100 t i m e s more p o t e n t t h e n L - P r o p i o n i l c a r n i t i n e . T h i s e f f e c t is not related to an adrenergic or cholinergic m e c h a n i s m . DL-Acetylcarnetine present also a positive inotropic effect u n d e p e n d e n t of cardiac B-adrenergic stimulation~ whilst L-Propionilcarnitine h a d a dose d e p e n d e n t negative inotropic effect at a dose between 10-3 M a n d 10 -2 M. W h e n administred at lower d o s a g e L-Propionilcar nitine did not altered cardiac contractility.