Nyadjeu Paulin, Dongmo Alain, Nguelefack Télesphore Benoît, Kamanyi Albert
University of Dschang.
J Complement Integr Med. 2011 Jan;8. doi: 10.2202/1553-3840.1490.
The present study was undertaken to evaluate the antihypertensive and vasorelaxant effects of Cinnamomum zeylanicum Blume stem bark aqueous extract in rats. The in vivo activities of the extract were evaluated on normotensive and three rat models of hypertension while the in vitro tests were assayed on rat isolated aorta rings. Acute intravenous injection of the extract (5, 10 and 20mg/kg) induced a significant reduction in mean arterial blood pressure in anaesthetised normotensive Wistar rats, salt-loaded hypertensive, L-NAME hypertensive and spontaneously hypertensive rats. Pre-treatment of rats with either propranolol or atropine significantly inhibited the hypotensive effects of the plant extract suggesting its possible action through the interferences with both cholinergic and sympathetic transmissions. Moreover, pre-treatment of rats with L-NAME inhibited the sustained plant antihypertensive effects, suggesting a possible active vasodilatation, which might be partly mediated by an endothelial l-arginine/nitric oxide pathway. In isolated rat aortic rings pre-contracted with KCl (60mM), the extract exhibited cumulative vasodilating effects, which were attenuated with either L-NAME, vascular endothelium removal or both tetraethylammonium and glibenclamide pre-treatments. The vasorelaxant effects may be involved in the extract antihypertensive mechanism, partially by increasing the endothelial nitric oxide and by activating the KATP channels in vascular smooth muscle.
本研究旨在评估锡兰肉桂茎皮水提取物对大鼠的降压和血管舒张作用。在正常血压大鼠和三种高血压大鼠模型上评估了该提取物的体内活性，同时在大鼠离体主动脉环上进行了体外试验。对麻醉的正常血压Wistar大鼠、盐负荷性高血压大鼠、L- NAME高血压大鼠和自发性高血压大鼠急性静脉注射该提取物（5、10和20mg/kg）可显著降低平均动脉血压。用普萘洛尔或阿托品预处理大鼠可显著抑制该植物提取物的降压作用，表明其可能通过干扰胆碱能和交感神经传递发挥作用。此外，用L- NAME预处理大鼠可抑制该植物提取物的持续降压作用，提示可能存在有效的血管舒张作用，这可能部分由内皮型一氧化氮合酶/一氧化氮途径介导。在预先用氯化钾（60mM）预收缩的离体大鼠主动脉环中，该提取物表现出累积的血管舒张作用，而L- NAME、去除血管内皮或四乙铵和格列本脲预处理均可减弱这种作用。血管舒张作用可能参与了该提取物的降压机制，部分是通过增加内皮一氧化氮和激活血管平滑肌中的ATP敏感性钾通道实现的。
