Cardiovascular effects of piperine in anaesthesized dogs

Abstract

Cardiovascular responses to intravenous administration of piperine were investigated in anaesthetized dogs. Piperine produced biphasic effects on the arterial blood pressure, depressor and pressor effects. In the presence of vagus nerves, low doses of piperine (0.25-0.5 mg kg -1 ) caused a transient drop in arterial blood pressure, a marked bradycardia and apnea. With higher doses of piperine (1.0-1.5 mg kg -1 ), a transient drop in blood pressure was followed by an overshoot of pressure and then a rapid return to normal. Bilateral vagotomy or atropine injection (1.0 mg kg -1 ) abolished the bradycardia and the fall of blood pressure caused by piperine. Regarding the pressor effect, piperine produced a positive inotropic effect with no chronotropic action. Verapamil (0.15 mg kg -1 ), a calcium channel blocking agent, completely abolished the overshoot of blood pressure. These results suggest that the depressor effect of piperine is associated with a cholinergic mechanism whereas the pressor effect is related to an influx of Ca ++ into the muscle cells probably into the cardiac and vascular smooth muscle cells.