A-80b is a synthesized pyridazino[4,5-b]indole derivate. A 80b shows potent and long-lasting antihypertensive activity and lowers blood pressure. The decrease in diastolic pressure was greater than the decrease in systolic pressure and cardiac frequency was not modified significantly. A-80b shows dose-dependent inhibition of the Ca(2+)-induced contraction. A-80b exerts a hypotensive and antihypertensive effect, possibly attributable to vasodilator activity via interference with Ca2+ influx and probably Ca2+ mobilization from intracellular stores.
