Ojewole John A O
Department of Pharmacology, Faculty of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Cardiovasc J S Afr. 2006 May-Jun;17(3):117-23.
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.
在大鼠实验模型中研究了比氏硬核树茎皮水提取物的血管舒张和降压作用。向浴液中累积添加比氏硬核树茎皮水提取物（SBE 12.5 - 200 mg/ml）可引起预先用去甲肾上腺素（NA）预收缩的含内皮正常血压Wistar大鼠离体主动脉环浓度依赖性舒张。去除功能性内皮（在去内皮正常血压Wistar大鼠离体主动脉环中），或用一氧化氮合酶（NOS）抑制剂NG-硝基-L-精氨酸甲酯（L-NAME）预处理含内皮的离体主动脉环，均可消除SBE对含内皮离体主动脉环的血管舒张作用。静脉推注该植物提取物（SBE 25 - 400 mg/kg iv）可使麻醉的正常血压和高血压Dahl盐敏感大鼠的全身动脉血压和心率出现短暂、剂量依赖性且显著（p < 0.05 - 0.001）的降低。这项实验动物研究的结果表明，比氏硬核树茎皮水提取物通过内皮依赖性一氧化氮（NO）使正常血压Wistar大鼠主动脉血管平滑肌舒张；并且该植物提取物的降压作用可能至少部分是通过一氧化氮合酶激活及随后一氧化氮释放介导的。
