title: Mechanism of the hypotensive action of Rhazya stricta leaf extract in rats.
abstract: 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 naiuml;ve 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.
authors.affiliation: Department of Pharmacology, College of Medicine, Sultan Qaboos University, Muscat, 123.
authors.forename: M O
authors.initials: MO
authors.lastname: Tanira
authors.forename: B H
authors.initials: BH
authors.lastname: Ali
authors.forename: A K
authors.initials: AK
authors.lastname: Bashir
authors.forename: S
authors.initials: S
authors.lastname: Dhanasekaran
authors.forename: E M
authors.initials: EM
authors.lastname: Tibiriçá
authors.forename: L M
authors.initials: LM
authors.lastname: Alves
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004573:Electrolytes / Q000494:pharmacology; D005612:Freeze Drying; D006339:Heart Rate / Q000187:drug effects; D006851:Hydrochloric Acid / Q000378:metabolism; D008297:Male; D010936:Plant Extracts / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000470:Alkaloids; D000959:Antihypertensive Agents; D004573:Electrolytes; D010936:Plant Extracts; D006851:Hydrochloric Acid