n Cardiovascular Journal of South Africa - Vasorelaxant and hypotensive effects of (A Rich) Hochst (Anacardiaceae) stem bark aqueous extract in rats : cardiovascular topic




The vasorelaxant and hypotensive effects of <I>Sclerocarya birrea&lt;/I&gt; stem bark aqueous extract have been examined in rat experimental paradigms. Cumulative additions of <I>S birrea&lt;/I&gt; 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 N<SUP>G</SUP>-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS). <BR>Bolus intravenous administrations of the plant extract (SBE 25-400 mg/kg iv) caused transient, dose-dependent and significant (&lt;I&gt;p&lt;/I&gt; < 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 <I>S birrea&lt;/I&gt; 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.


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