Reduction of size of myocardial infarction with nicorandil, a new antianginal drug, after coronary artery occlusion in dogs.

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 injected 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 micrograms/kg of nicorandil followed by a continuous infusion of 30 micrograms/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 less than 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%.