The hypotensive action of Rhazya stricta lyophilized leaf extract was found to be partly caused by the electrolyte content of the extract, and partly caused by a strongly basic alkaloidal fraction (AF). AF (0.05-1.6 mg animal-1) caused a dose-dependent reduction in mean arterial blood pressure (MAP) of urethane-anaesthetized rat preparations. In naive pithed rats, AF administration (0.5-2.0 mg animal-1) significantly increased MAP. In pithed or spinalized rats made normotensive by noradrenaline infusion, AF (0.25 mg animal-1) did not cause any significant changes. Direct intracerebroventricular injection of AF (0.1-0.4 mg) markedly and significantly reduced MAP. It is suggested that the hypotensive action of AF to be mediated by a central mechanism. (C) 2000 Academic Press.
- Intracerebroventricular (icv)
- Rhazya stricta
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