Terminalia bellerica 對於抗高血壓功效之藥物動力學評估   全文下載

Pharmacodynamic Evaluation of Terminalia bellerica for Its Antihypertensive Effect

Terminalia bellerica 已在許多疾病，包括高血壓上，被用來當作一種民間藥。我們的目的在於研究其降血壓的可能機轉。Terminalia bellerica 果實（tb.Cr）之粗萃取物被檢測出有類黃酮、固醇及丹寧，對於麻醉中的大鼠，會誘發劑量依存（10-100 mg/kg）的動脈血壓下降。在分離出的天竺鼠心房中，tb.Cr 抑制動脈收縮的力量及速率。在兔子的胸主動脈中，tb.Cr 減輕phenylephrine（Pe，1 μM）及K+（80 mM）導致的收縮，也會抑制無Ca++培養皿中Pe（1 μM）所控制的高峰，作用效果類似verapamil。在內皮細胞未受損傷的大鼠之主動脈製備時，當非受Nω-nitro-L-arginine methyl ester 妨礙下，tb.Cr 的血管擴張效應與內皮細胞無關；同樣的收縮發生在內皮細胞裸露的組織。這些結果顯示，Terminalia bellerica 藉由抗Ca++ 機轉降血壓，此提出合理的機轉背景以供高血壓之醫療用途。

Terminalia bellerica has been used as a folk medicine in a variety of ailments including hypertension. Our aim was to investigate the possible mechanism of its blood pressure (BP)-lowering effect. The crude extract of Terminalia bellerica fruit (Tb.Cr) which tested positive for flavonoids, sterols and tannins induced a dose-dependent (10-100 mg/kg) fall in the arterial BP of rats under anaesthesia. In isolated guinea-pig atria, Tb.Cr inhibited the force and rate of atrial contractions. In rabbit thoracic aorta, Tb.Cr relaxed the phenylephrine (PE, 1 μM) and K+ (80 mM)-induced contractions as well as suppressed the PE (1 μM) control peaks in the Ca++-free medium, similar to that caused by verapamil. The vasodilator effect of Tb.Cr was endothelium-independent as it was not opposed by Nω-nitro-L-arginine methyl ester in endothelium-intact rat aortic preparations and it occurred at the similar concentration in the endothelium-denuded tissues. These results indicate that Terminalia bellerica lowers BP through Ca++ antagonist mechanism and thus provides a sound mechanistic background for its medicinal use in hypertension.