In anesthetized cats, intravenous administration of nonachlazin (1 and 6 mg/kg) and ethmozine (2 and 5 mg/kg) led, 5 minutes after ligation of the anterior descending branch of the left coronary artery, to the increased blood outflow from the coronary sinus and to a less marked elevation of myocardial oxygen consumption. The coronarodilatory effect of the drugs fell in the presence of a preliminary injection of the sympatholytic octadin (25 mg/kg intraperitoneally), atropine (0.5 mg/kg intravenously), alpha-adrenoblocker dihydroergotoxin (2 mg/kg intravenously), and beta-adrenoblocker obsidan (0.5 mg/kg intravenously). Nonachlazin and ethmozine decreased the pituitrin-induced (2 ED/kg intravenously) spasm of the coronary vessels of the affected heart.