[Effects of 5-(3-tert-butylamino-2-hydroxy) propoxy-3,4-dihydrocarbostyril hydrochloride(OPC-1085) on coronary circulation and myocardial metabolism].

Effects of a new beta-adrenergic blocking agent, 5-(3-tert-butylamino-2-hydroxy) propoxy-3,4-dihydrocarbostyril hydrochloride (OPC-1085), on the coronary circulation and myocardial metabolism were investigated in anesthetized open-chest dogs and isolated perfused dog hearts. In anesthetized open-chest dogs, OPC-1085 antagonized the responses to isoproterenol of heart rate, Vmax, mean blood pressure, myocardial oxygen consumption, coronary blood flow and redox potential. The antagonistic potency of OPC-1085 was stronger than propranolol. OPC-1085 3 to 30 mug/kg caused appreciable decreases, but in doses of 100 to 1,000 mug/kg caused increases in heart rate and Vmax. The effect of OPC-1085 on max dp/dt was similar to that on Vmax. However, propranolol 3 to 3,000 mu-g/kg caused only decreases in heart rate, Vmax and max dp/dt. OPC-1085 3,10 mu-g/kg while propranolol 30, 100 mu-g/kg caused a fall in myocardial oxygen consumption and coronary blood flow. In isolated perfused hearts, intracoronary injection of OPC-1085 0.1 mg almost completely suppressed isoproterenol-induced augmentation of heart rate, myocardial contractile force and coronary blood flow and reduction of redox potential. OPC-1085 0.1 mg caused slight increases in heart rate, myocardial contractile force and myocardial oxygen consumption. It is concluded that OPC-1085 is a more potent beta-adrenergic blocking agent than propranolol and possesses a weak negative inotropic effect in doses of 3 to 30 mu-g/kg and a intrinsic sympathomimetic activity in doses of 100 to 1,000 mu-g/kg.