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Effects of oxygen free radicals on membrane fluidity of human erythrocytes
J Mol
Cell
Cardiol
21 (Supplement
382
DIRECI EFFECT OF HYDROGEN PEROXIDE (H202) ON MYOCARDIAL FUNCTION AND STRUCTURE. T.Gnodera, P.Srivastava, M.Ashraf. Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA Previously, we reported that H202 rather than superoxide radicals generated from xanthine and xanthine oxidase reaction induced eevere myocardial damage. In this study, we evaluated the direct effect of exogenous H202 (loo-3OO@l) on isolated rat hearts (H). With 100~M H202, dP/dt did not change after 20min. infusion. With 200@ H202, dP/dt decreased to 38% of control values after 15min. and ventricular fibrillation (VF) occurred after 20min. When 2OOuM H202 was discontinued at lSmin., dP/dt returned to 06% after 15min. With 3OOuM H202, dP/dt decreased to 23% after 1Omin. and VP occurred after 15min. Following discontinuation of 3OOuM H202 at lOmin., dP/dt returned to 92% after 15min. When 16mEq of K+ was added to prevent VF in H perfused with 3OO@l HZ02 for 15&n., dP/dt returned to 66% after 15min. With 3OO@l H202 for 20min., even in the presence of 16mEq K+, the heart beat did not return. Tissue ATP was 5.461.4 umol/gdw in H with VF and 16.2i2.8 umol/gdw in H with almost normal function. Morphological changes were severe in H with VF and were milder in H with almost normal function. Our data suggest that l)the effect of 300@ HZ02 for 10min. and ZOO@ H202 for 15min. is reversible. 2)the effect of 3OOPl-l H202 for 2Omin. is irreversible. 3)the administration of Ii202 mimics the effect of myocardial stunning. Supported by a NIH grant, HL23597
383
EFFECTS OF OXYGEN FREE RADICALS ON MEMBRANE FLUIDITY OF HUMAN ERYTHROCYTES. A.Kobayashi, H.Watanabe, H,Hayashi, N.Yamazaki. Third Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan. Oxygen free radicals have been proposed to cause lipid peroxidation of biomembranes, and play an important role in myocardial cell damages during ischemia and reperfusion. To characterize alterations in membrane molecular dynamics caused by oxygen free radicals, human erythrocytes were spin-labeled with 5-doxyl stearic acid, and alterations in membrane fluidity were quantified by electron resonance spectrometry. Membrane fluidity decreased in vitro generation of oxygen free radicals by hypoxanthine(0.43mM)-xanthine oxidase(O.O7units/ml). The addition of superoxide dismutase(lOOU) and catalase(O.O3mg/ml) inhibited the decrease of membrane fluidity induced by hypaxanthine-xanthine oxidase. Hydrogen peroxide (O.OlmM, 0.11134, 1mM) decreased membrane fluidity in a concentration dependent that alterations in molecular dynamics are one manner . These results suggest mechanism through which oxygen free radicals could play an important role in cardiac cell damages during ischemia and teperfusion.
384
PREVENTION BY SUPEROXIDE DISMUTASE (SOD) OF CARDIAC REPERFUSION INJURY IN VITRO T and Sjijqvist P.O., dept of REQUIRES PR!Z-ISCHEMIC ADMINISTRATION. Abrahamsson, Cardiovascular Pharmacol. Hassle res. Labs., Mijlndal, Sweden. In the isolated Krebs perfused rat heart left ventricular dP/dt max was measured using an intra-ventricular ballon. The left coronary artery was ligated for 30 min followed by a 30 min reperfusion period. Creatine kinase (CK) activity was Bovine CuZn-SOD (2Omg/l-: 1OOOOOIIJ/1) analyzed during reperfusion in the effluent. was either added to the buffer during the entire perfusion period (ICR) or added, startins 5 min prior to reperfusion (R). II= number of exDeriments. dP/dt mx n CK %recoverV of dP/dt max (prior to I) Smin(R) 25&n(R) (IU/3Omin) Untreated 14 SOD (I+R) 8 8 SOD (R) (mean values * SEM) It is concluded that ventricular function prior to the ischemic ischemic effect rather
II) (1989)
71f6 53*5*
4367i308 4125f251
79*3 80f4 78f3
77f3 89f2** 79+3
79fll 4919f361 * p
S.128
left started anti-
Cell
Cardiol
21 (Supplement
382
DIRECI EFFECT OF HYDROGEN PEROXIDE (H202) ON MYOCARDIAL FUNCTION AND STRUCTURE. T.Gnodera, P.Srivastava, M.Ashraf. Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA Previously, we reported that H202 rather than superoxide radicals generated from xanthine and xanthine oxidase reaction induced eevere myocardial damage. In this study, we evaluated the direct effect of exogenous H202 (loo-3OO@l) on isolated rat hearts (H). With 100~M H202, dP/dt did not change after 20min. infusion. With 200@ H202, dP/dt decreased to 38% of control values after 15min. and ventricular fibrillation (VF) occurred after 20min. When 2OOuM H202 was discontinued at lSmin., dP/dt returned to 06% after 15min. With 3OOuM H202, dP/dt decreased to 23% after 1Omin. and VP occurred after 15min. Following discontinuation of 3OOuM H202 at lOmin., dP/dt returned to 92% after 15min. When 16mEq of K+ was added to prevent VF in H perfused with 3OO@l HZ02 for 15&n., dP/dt returned to 66% after 15min. With 3OO@l H202 for 20min., even in the presence of 16mEq K+, the heart beat did not return. Tissue ATP was 5.461.4 umol/gdw in H with VF and 16.2i2.8 umol/gdw in H with almost normal function. Morphological changes were severe in H with VF and were milder in H with almost normal function. Our data suggest that l)the effect of 300@ HZ02 for 10min. and ZOO@ H202 for 15min. is reversible. 2)the effect of 3OOPl-l H202 for 2Omin. is irreversible. 3)the administration of Ii202 mimics the effect of myocardial stunning. Supported by a NIH grant, HL23597
383
EFFECTS OF OXYGEN FREE RADICALS ON MEMBRANE FLUIDITY OF HUMAN ERYTHROCYTES. A.Kobayashi, H.Watanabe, H,Hayashi, N.Yamazaki. Third Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan. Oxygen free radicals have been proposed to cause lipid peroxidation of biomembranes, and play an important role in myocardial cell damages during ischemia and reperfusion. To characterize alterations in membrane molecular dynamics caused by oxygen free radicals, human erythrocytes were spin-labeled with 5-doxyl stearic acid, and alterations in membrane fluidity were quantified by electron resonance spectrometry. Membrane fluidity decreased in vitro generation of oxygen free radicals by hypoxanthine(0.43mM)-xanthine oxidase(O.O7units/ml). The addition of superoxide dismutase(lOOU) and catalase(O.O3mg/ml) inhibited the decrease of membrane fluidity induced by hypaxanthine-xanthine oxidase. Hydrogen peroxide (O.OlmM, 0.11134, 1mM) decreased membrane fluidity in a concentration dependent that alterations in molecular dynamics are one manner . These results suggest mechanism through which oxygen free radicals could play an important role in cardiac cell damages during ischemia and teperfusion.
384
PREVENTION BY SUPEROXIDE DISMUTASE (SOD) OF CARDIAC REPERFUSION INJURY IN VITRO T and Sjijqvist P.O., dept of REQUIRES PR!Z-ISCHEMIC ADMINISTRATION. Abrahamsson, Cardiovascular Pharmacol. Hassle res. Labs., Mijlndal, Sweden. In the isolated Krebs perfused rat heart left ventricular dP/dt max was measured using an intra-ventricular ballon. The left coronary artery was ligated for 30 min followed by a 30 min reperfusion period. Creatine kinase (CK) activity was Bovine CuZn-SOD (2Omg/l-: 1OOOOOIIJ/1) analyzed during reperfusion in the effluent. was either added to the buffer during the entire perfusion period (ICR) or added, startins 5 min prior to reperfusion (R). II= number of exDeriments. dP/dt mx n CK %recoverV of dP/dt max (prior to I) Smin(R) 25&n(R) (IU/3Omin) Untreated 14 SOD (I+R) 8 8 SOD (R) (mean values * SEM) It is concluded that ventricular function prior to the ischemic ischemic effect rather
II) (1989)
71f6 53*5*
4367i308 4125f251
79*3 80f4 78f3
77f3 89f2** 79+3
79fll 4919f361 * p
S.128
left started anti-