Abolition of spontaneous rhythmic contractions of isolated monkey coronary arteries by diltiazem, nifedipine, verapamil and nicorandil but not by nitroglycerin.

ISHII, K., YANAGISAWA, T., SATOH, K. and TAIRA, N. Abolition of Spontaneous Rhythmic Contractions of Isolated Monkey Coronary Arteries by Diltiazem, Nifedipine, Verapamil and Nicorandil but Not by Nitroglycerin. Tohoku J. exp. Med., 1985, 145 (1), 85-90-Three of 12 coronary artery rings obtained from one of 9 rhesus monkeys (Macaca mulatta) (113 rings in all) and 4 of 12 coronary artery rings obtained from one of 2 patas monkeys (Erythrocebus patas patas) (28 rings in all) developed spontaneous rhythmic contractions. In 5 of these 7 coronary artery rings, rhythmic contractions occurred long enough to be subjected to examinations of drug effects. In these preparations the effects of the calcium entry blockers, diltiazem, nifedipine and verapamil, and nicorandil, a nitrate vasodilator thought to produce vasodilatation by an increase in membrane potassium permeability, and nitroglycerin were investigated on rhythmic contractions. Diltiazem (10-7 and 10-6M), nifedipine (10-8 and 10-7M), verapamil (10-7 and 10-6M) and nicorandil (10-5 and 10-4M) suppressed rhythmic contractions in a concentration-dependent manner, but nitroglycerin (10-7-10-5M) was entirely ineffective. The results were discussed in relation to the mechanisms underlying spontaneous rhythmic contractions of coronary arteries and their role in vasospastic angina pectoris.