甲基莲心碱降低血压及松弛血管作用的分析

甲基莲心碱(neferine,Nef)对自发性高血压大鼠有明显的降压作用,ig给药降压作用可维持3h以上。对由高钾去极化引起的兔主动脉环收缩的抑制作用为维拉帕米(verapamil,Ver)的1/792,使CaCl_2及甲氧明(methoxamine,Met)的量效曲线平行右移,最大反应前者压低、后者不变,pD_2及pA_2值分别为5.4及6.3。还抑制由去甲肾上腺素(norepinephrine,NE)引起的依内钙收缩反应,提示Nef对α_1肾上腺素受体有阻断作用及较弱的钙拮抗作用。

An analysis of depressive effects of neferine on blood pressureand blood vessels

Neferine has a significant antihyper-tensive effect on the conscious spontaneously hypertensive rats. If neferine was given orally to the spontaneously hypertensive rats (40 mg / kg), it caused a long-lasting decreasing systolic blood pressure (SP). The effects of neferine on the isolated rabbit aortic ring were compared with those of verapamil and prazosin. Neferine could inhibit the contraction induced by high-KC1, but this action was 792 times less than that of verapamil. Both of them shifted the CaCl2 dose-response curves to the right in a parallel fashion and decreased the maximal response, which indicated a noncompetitive antagonism. Neferine, similar toprazosin, antagonised methoxamine in a competitive manner. Neferine and verapamil obviously decreased the intracellular Ca-dependent contraction induced by noradrenaline but no effect on extracellular Ca2+ dependent component was observed. The results suggested that neferine was a potential calcium antagonist and had a relatively potent inhibitory effect on a1-adrenoceptor.