Effect of nifedipine and niludipine on myocardial pH in the ischemic canine heart.

The effect of nifedipine and niludipine on ischemic myocardial pH was studied. To make the myocardium ischemic (60% reduction of coronary flow), the left anterior descending coronary artery (LAD) was partially occluded 30 min before either vehicle (1% ethanol solution) or drugs were injected intravenously. In the non-occlusion group, nifedipine (10 micrograms/kg) and niludipine (10 micrograms/kg) increased coronary flow, decreased blood pressure, and did not change myocardial pH appreciably. In the partial occlusion group, reduction of coronary flow decreased the myocardial pH, increased ST segment, and did not change heart rate and blood pressure. Vehicle was injected 30 min after the occlusion, but did not change any of the parameters. A small dose (1 microgram/kg) and a large dose (10 micrograms/kg) of nifedipine, and niludipine (10 micrograms/kg) did not exert any beneficial effect on the myocardial pH, coronary flow and the ST segment during coronary occlusion.