ENDOGENOUS ANTIOXIDANTS IN ISOLATED HYPERTROPHIED CARDIAC MYOCYTES AND HYPOXIA-REOXYGENATION INJURY

Effects of hypoxia-reoxygenation (H-R) on myocytes isolated from 10 we ek hypertrophied and sham control rat hearts were studied, Myocyte hyp ertrophy was indicated by an increase in cell size. Superoxide dismuta se (SOD) and glutathione peroxidase (GSHPx) enzyme activities were sig nificantly higher and lipid peroxidation (TEARS) was lower in hypertro phied myocytes prior to any H-R, Hypertrophied myocyte population show ed significantly less damage to cell morphology due to H-R. In sham as well as hypertrophied myocytes, Na+ and Ca2+ contents were increased by H-R, but Ca2+ accumulation was significantly less in the hypertroph ied myocytes. Both SOD and GSHPx activities were depressed by the oxid ative stress in the sham myocytes whereas these activities were not si gnificantly changed in the hypertrophied myocytes. Catalase activity i n the prehypoxic sham and hypertrophied myocytes was comparable and th is activity did not change during H-R. There was a significant increas e in lipid peroxidation due to H-R but this change was less in hypertr ophied myocytes. This study shows less vulnerability of hypertrophied myocytes to oxidative stress and an increase in endogenous antioxidant reserve may have an important; role in mediating this protection.