Department of Pharmacology, Chiang Mai University, Chiang Mai, Thailand.
J Nat Med. 2011 Jul;65(3-4):551-8. doi: 10.1007/s11418-011-0540-z. Epub 2011 May 10.
The cardiovascular effects of the water extract from fresh leaves of P. palatiferum (PP) were evaluated in rats in both in vivo and in vitro models. The PP extract consisted of alkaloids, coumarins and sterols. The extract (5-25 mg/kg, I.V.) decreased both the mean arterial blood pressure and heart rate of normotensive and L: -N-(ω)-nitro-arginine methyl ester (L: -NAME)-induced hypertensive anesthetized rats. The extract caused relaxation of the norepinephrine-contracted endothelium-intact aorta ring (EC(50) = 81.0 μg/mL). Functional removal of the endothelium attenuated the vasodilatation effect of the extract (EC(50) = 136.4 μg/mL). Pretreatment with L: -NAME or atropine did not alter the vasodilation effect of the extract. Pre-incubation with atropine did not alter bradycardic effect of the extract on isolated rat atrium. The effects of isoproterenol on isolated atrium were attenuated by the extract (2.5-5 mg/mL). In conclusion, the water extract from fresh leaves of P. palatiferum possessed hypotensive and bradycardic effects. The vasorelaxant effect of the extract was dependent partly on the vascular endothelium but was not dependent on the synthesis of nitric oxide and did not act through activation of the muscarinic receptor.
从鲜叶中提取的水的心血管作用 palatiferum (PP) 在体内和体外模型中都在大鼠进行了评价。PP 提取物由生物碱、香豆素和固醇组成。该提取物（5-25mg/kg，静脉注射）降低了正常血压和 L: -N-（ω）-硝基-精氨酸甲酯（L: -NAME）诱导的高血压麻醉大鼠的平均动脉血压和心率。该提取物引起去甲肾上腺素收缩的内皮完整主动脉环松弛（EC50=81.0μg/mL）。内皮功能去除减弱了提取物的血管扩张作用（EC50=136.4μg/mL）。L: -NAME 或阿托品预处理不会改变提取物的血管扩张作用。阿托品预先孵育不会改变提取物对分离大鼠心房的心动过缓作用。异丙肾上腺素对分离心房的作用被提取物（2.5-5mg/mL）减弱。结论：从鲜叶中提取的水 palatiferum 具有降压和减慢心率的作用。提取物的血管舒张作用部分依赖于血管内皮，但不依赖于一氧化氮的合成，也不通过激活毒蕈碱受体起作用。
