Cardiovascular Effects of Bulbocapnine

Upon intravenous injection of bulbocapnine into the dog, myocardial ventricular contractile force was altered and the mean arterial blood pressure was markedly lowered. Following a 50-mg./kg. dose of bulbocapnine, the blood pressure and contractile force effects of 5-hydroxytryptamine became negligible. Injections of norepinephrine, epinephrine, and isoproterenol in doses of 1 mcg./kg. and of ethylnorepinephrine in a dose of 50 mcg./kg. showed reduced effects on mean arterial blood pressure and contractile force. The effects of none of these were reversed by bulbocapnine. Animals treated with bulbocapnine, 25 mg./kg. i.p. for 5 days, became more sensitive to injections of 5-hydroxytryptamine, norepinephrine, epinephrine, and isoproterenol, as was seen in consistently altered diastolic blood pressure and contractile force effects.