血管壁内脑啡肽抑制效应的受体途径分析

我们以前的实验证明,离体兔耳动脉壁中含有脑啡肽,它对去甲肾上腺素的释放有抑制作用,并使血管收缩反应明显下降。脑啡肽的这一抑制效应是通过突触前和突触后的途径实现的。本实验进一步提示,脑啡肽抑制效应的突触前膜受体途径也可能有两条。一是突触前膜上的阿片受体被脑啡肽激活后,直接抑制去甲肾上腺素的释放;另一是阿片受体被激活后,再通过激活前膜上的α_2—肾上腺素能受体,从而对去甲肾上腺素的释放和血管收缩反应发生负反馈作用。本实验还证明,脑啡肽的这一抑制效应是不需要前列腺素参与作用的。脑啡肽这一抑制效应的存在,对血管活动的调节和实际应用都可能具有重要的意义。

THE RECETOR ROUTE OF INHIBITORY EFFECT OF ENKEPHALIN ON THE BLOOD VESSEL WALL

We have reported that enkephalins produced in artery vall can inhibit the release of noradrenaline from sympathetic nerve terminals and the artery strip contraction which occurs during electrical field stimulation. In the present study, we show that there are two receptor routes responsible for these inhibitory effects. First, after having been activated by enkephalins, the opiate receptors on the presynaptic membrane inhibit directly the release of noradrenaline. Secondly, the active opiate receptors activate the a2- receptors on the presynaptic membrane, which in turn, induce the negative mechanism of the release of noradrenaline and result in the inhibition of artery vessel contraction. The study indicates also that these inhibitory actions of enkephalins may occur without the pretence of prosta-glandines (PGS).