[Activity of lysosomal enzymes in isolated perfused rat heart in reversible ischemia and post-ischemic reperfusion with administration of dibutyryl-cAMP and isoproterenol].

Activity of lysosomal enzymes and lipid peroxidation as well as effects of dibutyryl-cAMP and isoproterenol, which increased the intracellular content of cAMP, on the state of lysosomal membranes were studied in isolated perfused rat heart under conditions of reversible ischemia and subsequent reperfusion. The ischemia and especially postischemic reperfusion led to activation of acid hydrolases in sarcoplasmic reticulum and of lipid peroxidation: content of malonic dialdehyde was increased in heart tissue. Addition of dibutyryl-cAMP or isoproterenol into the perfusion solution at concentrations not affecting the heart systole caused a decrease in activity of lysosomal enzymes in sarcoplasm as well as in the rate of lipid peroxidation. A decrease in the lysosomal membranes lability and in the rate of lipid peroxidation appear to prevent the irreversible impairments of cardiomyocytes in ischemia particularly within the first minutes of postischemic reperfusion. Possible mechanisms of lysosomal membranes stabilization under conditions of reversible ischemia and postischemic reperfusion are discussed.