Comparison of cardiovascular effects of aconite root and higenamine in dogs

The effects of aconite root and higenamine(dl-demethylcoclaurine) on the hemodynamics were compared in 13 anesthetized dogs. Their effects on blood pressure and heart rate were compared in 4 conscious dogs. Blood flow was measured by means of electromagnetic flow meter. After intravenous injections of the aqueous-alcoholic extract of processed aconite root which was used in the clinic, the coronary and femoral blood flows increased, the vascular resistance of coronary, femoral and internal carotid arteries decreased, while the cardiac index and stroke index as well as myocardial O2 consumption elevated. These effects of aconite were found to be similar to that of higenamine 5 g/kg.In anesthetized dogs,no significant changes in blood pressure and heart rate were observed after intravenous administration of aconite root 2 g/kg, whereas tachycardia and hypotension were obvious after intravenous injections of higenamine 5 g/kg in anesthetized dogs. In conscious dogs iv aconite elicited both hypertension and tachycardia. The augmentations of diastolic blood pressure and heart rate induced by the aconite were slightly depressed by a pretreatment with reserpine. The tachycardia in conscious dogs and the augmentation of coronary blood flow and myocardial O2 consumption in anesthetized dogs were partly antagonized by the beta-adrenoreceptor antagonist-propranolol. The pressor effect in conscious dogs elicited by aconite was reversed to a depressor one after the alpha-blocker-phentolamine. This indicates that there are some differences between the cardiovascular effects of aconite root and higenamine,the latter is a beta-agonist while the former probably has both alpha- and beta-adrenoreceptor stimulating effects.