Responses of dog large coronary arteries to constrictor and dilator substances: implications for the cause and treatment of variant angina pectoris.
JA Angus, RM Brazenor, MA Le Duc
Am J Cardiol | Published : 1983
Canine circumflex coronary artery ring segments were mounted in organ baths and contracted by ergonovine (ergometrine), serotonin, phenylephrine, norepinephrine (in the presence of propranolol), potassium (K+) and a thromboxane A2 mimetic, U46619. Ergometrine was classified as a serotonin agonist since concentration-response curves were competitively inhibited by methysergide but not by alpha-adrenoceptor antagonists. Arteries precontracted to 80% of maximum were relaxed by verapamil, nifedipine and glyceryl trinitrate. However, nifedipine was 100-fold more potent against K+ than either serotonin- or phenylephrine-contracted vessels. Verapamil showed some selectivity for K+ and serotonin con..View full abstract