Abstract
Effects of a new adrenergic beta receptor blocking agent, YB-2 (1-(7-indenyloxy)-3-isopropylaminopropan-2-ol hydrochloride), on coronary circulation and myocardial metabolism, especially in interaction with catecholamines were investigated in isolated blood perfused and in situ heat preparations of the dog. In isolated hearts, intracoronary injection of YB-2 0.1mg did not produce any change in coronary blood flow (CBF), myocardial oxygen consumption (QO2) and redox potential (ΔEh), but caused a slight fall in perfusion pressure (PP) and appreciable decreases in heart rate (HR) and myocardial contractile force (MCF). At the same time, isoproterenol-induced augmentation of CBF, QO2, HR and MCF and reduction of ΔEh were greatly suppressed, while the hypotensive effect was converted to a hypertensive one.
In situ hearts, YB-2 0.1_??_0.2mg/kg i. v. produced significant reductions in HR, BP, CBF, CO, QO2 and CW, but caused a slight increase in ΔEh. Myocardial uptake and consumption of glucose were approx. the same as controls, while myocardial free fatty acid consumption was decreased after YB-2. YB-2 0.1mg/kg considerably depressed increases in HR, CO, CBF, QO2 and CW induced by epinephrine 1μg/kg i. v, and greatly enhanced the hypertensive effect of the amine.
It is concluded that YB-2 is a potent adrenergic beta receptor blocking agent and possibly effective as an anti-anginal agent.
