刺激家兔腹部迷走神经外周端引起的降压作用

本文对电刺激家兔腹部的迷走神经外周端所引起的降压反应进行了研究。在121只家兔中的实验结果表明:电刺激腹部迷走神经外周端可引起动脉压、小肠和后肢的灌流压同时降低,而心率则无明显变化。这一降压反应发生时,小肠静脉血中的组织胺含量较刺激前明显升高,然后恢复;将小剂量的组织胺 H_1受体阻断剂扑尔敏、非乃根和 H_2受体阻断剂甲氰咪胍(Cimetidine)分别注入肠系膜上动脉均能减弱刺激腹部迷走神经外周端引起的动脉压和小肠灌流压的降低。心得安能削弱此降压反应,而阿托品无效;切断两侧内脏大神经能显著削弱刺激腹部迷走神经外周端引起的降压反应。此残余的降压反应在注入抗组织胺剂后完全消失。由此推论,刺激家兔腹部迷走神经外周端引起的降压反应是通过中枢和外周两方面因素的作用,使血管舒张,外周阻力降低而实现的。

EFFECT OF STIMULATION OF PERIPHERAL END OF ABDO-MINAL VAGAL NERVE ON BLOOD PRESSURE IN RABBIT

The mechanism,of the depressor response produced by stimulation of the peri-pheral end of the abdominal vagal nerve in anesthetized rabbits was studied.The result of experiments on 121 rabbits showed that such a nerve stimula-tion in anesthetized rabbit caused a decrease in systemic blood pressure and alsoperfusion pressure of the hindlimb or small intestine but there was no significantchange in heart rate.During the depressor response due to nerve stimulationthe histamine content in the mesenteric venous blood was elevated markedly.In-jection of a small amount of H_1-or H_2-receptor antagonist into the superior me-senteric artery significantly reduced the depressor response of systemic blood pres-sure and also that of perfusion pressure of the small intestine.Propranolol couldalso decrease the depressor response to vagal nerve stimulation,but atropine hadno effect.Bilateral section of the splanchnic nerves markedly reduced the de-pressor response of the systemic blood pressure and that of perfusion pressure ofthe small intestine and hindlimb produced by vagus stimulation.The weakened de-pressor response after bilateral section of the splanchanic nerves was furtherabolished by the administration of histamine antagonist.It may be concluded thatthe depressor response caused by vagal nerve stimulation is due to a decrease inthe peripheral vascular resistance elicited by both peripheral and central factors.