[The role of free radical inhibitors of lipid peroxidation in protecting the myocardium from ischemic damage].

The natural antioxidant beta-carotene which, unlike phenol antioxidants such as dibunol and SPN-6, is capable of exhibiting antioxidative properties under low partial oxygen pressure (ischemia), has been found to increase the activity of antioxidative enzymes in the intact and infarct myocardium and to greatly exert a more antinecrotic action when given orally in a dose of 20 mg/kg in models of rat coronary-occlusion myocardial infarction than the phenol antioxidants mentioned above. Intravenous administration of copper-containing enzymes utilizing O2 superoxide dismutase (SOD), 4 mg/kg, or ceruloplasmin, 50 mg/kg, as with a highly disperse copper powder promoting a substantial increase in antioxidative enzyme activity in the rat myocardium has been demonstrated to reduce the zone of myocardial ischemic lesion in rats and to largely enhance postoperative survival rates in the animals. Three hours following intravenous SOD, an electron microscopic examination of rat ischemic myocardium showed a considerable fall in the structural and functional damages to cardiomyocytes in the periischemic area. The findings suggest that free radical processes make a contribution to ischemic cardiomyocyte lesion and open the way for pharmacological therapy of postischemic abnormalities with enzymatic and non-enzymatic preparations of antioxidants.