[Effect of experimental myocardial infarct on the succinate oxidation rate and succinate dehydrogenase activity in the heart mitochondria].

The rate of oxidation of NADH and 3-hydroxybutyrate was studied in heart mitochondria after short-term (60 min) occlusion of coronary artery and the subsequent reperfusion. Addition of NAD increased the rate of 3-hydroxybutyrate oxidation, lowered in mitochondria of impaired tissue, but no complete restoration occurred. The 3-hydroxybutyrate dehydrogenase activity was decreased by 25%. The rate of NADH oxidation in ultrasonicated mitochondria from the infarction zone exceeded 2-fold the rate of 3-hydroxybutyrate oxidation. These data suggest that deficiency of NAD limited primarily the rate of 3-hydroxybutyrate oxidation in heart mitochondria under conditions of experimental myocardial infarction. The level of 3-hydroxybutyrate dehydrogenase activity appears to restrict the rate of 3-hydroxybutyrate oxidation after addition of NAD.