Reduction of Size of Myocardial Infarction with Nicorandil, a New Antianginal Drug, After Coronary Artery Occlusion in Dogs

Abstract

The effects of nicorandil, a new antianginal drug, on size of myocardial infarction were studied in anesthetized, open-chest dogs after left anterior descending coronary artery occlusion. To quantify the extent of the hypoperfused zone, 99mTc-albumin microspheres were infected into the left atrium 1 min after occlusion. Fifteen minutes after occlusion, dogs were randomly assigned to a control group or a nicorandil-treated group that received immediately after assignments 100 .mu./kg of nicorandil followed by a continuous infusion of 30 .mu.g/kg/min for 6 h. Six hours after occlusion, the left ventricle was cut into 3 mm thick slices for triphenyltetrazolium chloride staining and autoradiography. The extent of the hypoperfused zone (26.1% .+-. 3.1% of the left ventricle in the control vs. 23.2% .+-. 3.7% in the treated group, mean .+-. SEM) was not different between the two groups. The ratio of the extent of myocardial necrosis to the extent of the hypoperfused zone was significantly smaller in the treated group (64.3% .+-. 7.2%, n = 7, p < 0.05) than in the control group (92.6% .+-. 9.2%, n = 7). Thus, nicorandil administered early after coronary artery occlusion reduced the size of myocardial infarction by 31%.