The effects of nicorandil (2-nicotinamidoethyl nitrate, SG-75) on the conductive coronary artery were studied and compared with the effects of nitroglycerin and nifedipine. In isolated perfused canine heart preparations with a support dog, nicorandil produced a decrease in the resistance of the conductive coronary artery at reduced perfusion pressures, whereas nitroglycerin had similar effects even at normal perfusion pressures. In anesthetized closed-chest dogs, nicorandil and nitroglycerin produced an increase in the diameter of the conductive coronary artery (nicorandil less than nitroglycerin). Nifedipine failed to produce dilatation of the conductive coronary artery in both preparations. In isolated ring preparations of conductive coronary artery, all three compounds produced relaxation of the potassium-induced contracture, but only nicorandil and nitroglycerin reversed the lanthanum-induced contracture.
Animals Coronary Vessels