Oxidative Status and Distribution of NADP-Dependent Isocitrate Dehydrogenase and Aconitate Hydratase in Rat Cardiomyocytes under Normal Conditions and during Ischemia

Oxidative status of rat cardiomyocytes during ischemia induced by occlusion of the descending branch of the coronary artery was studied by the methods of Fe-induced chemiluminescence and spectrophotometry of primary and secondary lipid peroxidation product. The concentrations of low-molecular-weight antioxidants a-tocopherol and citrate and activities of NADP-dependent isocitrate dehydrogenase (EC 1.1.1.41) and aconitate hydratase (EC 4.2.1.3) were also measured. Ischemia was associated with intensification of free radical processes, increased antioxidant activity in subcellular fractions of the myocardium, activation of NADP-isocitrate dehydrogenase, accumulation of citrate, and inhibition of aconitate hydratase. Differential centrifugation, ion exchange chromatography on various ion exchangers, and electrophoresis in polyacrylamide gel revealed no redistribution of enzyme activity between the cytoplasmic and mitochondrial cardiomyocyte fractions during ischemia.