title: Vasorelaxant and hypotensive effects of Sclerocarya birrea (A Rich) Hochst (Anacardiaceae) stem bark aqueous extract in rats.
abstract: The vasorelaxant and hypotensive effects of Sclerocarya birrea stem bark aqueous extract have been examined in rat experimental paradigms. Cumulative additions of S birrea stem bark aqueous extract (SBE 12.5-200 mg/ml) to the bath fluid induced concentration-dependent relaxations of endothelium- containing normotensive Wistar rat isolated aortic rings pre-contracted with noradrenaline (NA). The vasorelaxant effect of SBE on endothelium-containing isolated aortic rings was annulled by removal of the functional endothelium (in endothelium-denuded normotensive Wistar rat isolated aortic rings), or by pretreatment of the endothelium-containing isolated aortic rings with NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS). Bolus intravenous administrations of the plant extract (SBE 25-400 mg/kg iv) caused transient, dose-dependent and significant (p < 0.05-0.001) reductions in systemic arterial blood pressure and heart rates of anaesthetised normotensive and hypertensive Dahl salt-sensitive rats. The findings of this experimental animal study suggest that S birrea stem bark aqueous extract relaxes normotensive Wistar rat aortic vascular smooth muscle via endothelium-dependent nitric oxide (NO); and that the hypotensive effect of the plant extract is likely to be mediated, at least in part, through nitric oxide synthase activation and subsequent nitric oxide release.
authors.affiliation: Department of Pharmacology, Faculty of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: John A O
authors.initials: JA
authors.lastname: Ojewole
mesh_terms: D027926:Anacardiaceae; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology*; D018547:Plant Stems; D051381:Rats; D020303:Rats, Inbred Dahl; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D010936:Plant Extracts; D014662:Vasoconstrictor Agents; D009638:Norepinephrine