Endothelium modulated vasorelaxant response of a polypharmaceutical herbal drug (lipotab) and its individual constituents.

The present study was undertaken to examine the endothelium modulated effects of polypharmaceutical drug lipotab and its individual ingredients in isolated aortic rings of rat. Endothelium intact and denuded aortic rings were precontracted with phenylephrine 10(-6) M and drugs were added in cumulative manner in concentration ranging from 1 to 50 microg/ml. The results demonstrated an endothelium-dependent vasorelaxant effect of lipotab and its individual ingredients, with the exception of nicotinic acid. The dose dependent relaxant response of nicotinic acid was not altered significantly in the endothelium-denuded rings, suggesting a direct effect of the drug on the vascular smooth muscle. Vasorelaxant effect of lipotab and its individual constituents suggests the therapeutic potential of these compounds in certain cardiovascular diseases.

Effect of Ajmaloon on the baroreceptor-heart rate reflex in anaesthetized rabbits and monkeys.

The effects of a herbal drug, Ajmaloon (Hamdard, India), on the arterial blood pressure, heart rate (HR) and baroreceptor-heart rate reflex were studied in anesthetized rabbits and monkeys. Intravenously administered Ajmaloon produced a dose-dependent hypotensive response in both the species without any significant effect on the heart rate. Only in high doses (200 mg/kg or more). Ajmaloon produced a bradycardia response in rabbits. Even the highest dose (300 mg/kg) of Ajmaloon used in the present investigation did not cause arrhythmia or any other conduction disorder or respiratory distress. Baroreflex SAP-HR curve was shifted to the left of the control following treatment with 100 mg/kg intravenous Ajmaloon in both the species. Loss of tachycardia response to fall in arterial pressure in Ajmaloon treated animals indicated the drug induced suppression of normally existing sympathetic excitatory influence in response to hypotension. Baroreflex regulatory HR response to hypertension remains intact after intravenous administration of 100 mg/kg Ajmaloon, a dose much higher than the prescribed highest oral dose for humans. Intact baroreflex regulation of arterial blood pressure in response to hypertension in Ajmaloon treated mammals suggests that in patients besides lowering the blood pressure. Ajmaloon might not interfere with the normal blood pressure regulatory mechanism through arterial baroreceptors during hypertension.