It is now well known that oxygen free radicals act as mediators of cellular injury in many cardiovascular diseases. Although some evidences have been presented for an altered number of adrenergic receptors in heart disease, a detailed examination of the interaction of free radicals with cardiac adrenergic receptors has little been carried out.

This study is therefore undertaken to examine the influences of adrenergic blocking agents(propranolol, prazosin) and cyclooxygenase inhibitor(aspirin) on the cardiac damage by oxygen free radicals. Ischemic condition of the isolated rat heart was made by Langendorff preparation, and then measured superoxide dismutase(SOD), lactate dehydrogenase(LDH) released in the perfusate, and malondialdhyde(MDA) concentration in the cardiac tissue.

We obtained the results that increased SOD activity and tendency of decreased LDH activity by the pretreatment of propranolol, prazosin, and aspirin in cardiac ischemic-reperfusion injury. Those effects were more predominant in adriamycin treated group comparing with not treated group.

Adrenergic blocking agent, propranolol, prazosin, and aspirin seem to have some protective effect on the reperfusion injury of the heart.