家兔延髓腹侧表面加压区与压力感受性反射的关系

实验在乌拉坦麻醉、三碘季铵酚制动和人工呼吸的41只家兔进行。电刺激延髓腹侧面加压区(VSMp)引起肾交感神经电活动(RSNA)增强和动脉血压升高。电刺激主动脉神经(AN)则导致RSNA抑制和动脉血压下降。在下列实验条件下,刺激VSMp所致的交感兴奋性效应均不受影响:(1)同时刺激VSMp和AN;(2)刺激AN期间插入VSMp刺激;(3)刺激VSMp期间插入AN刺激。但刺激AN所致的交感抑制性效应却被明显地抑制。提示兴奋VSMp的交感兴奋性效应可调制压力感受性反射的交感抑制性成分,两者之间的动态平衡是维持静态动脉血压水平的基础。

RELATIONSHIP BETWEEN PRESSOR AREA OF VENTRAL SURFACE OF MEDULLA OBLONGATA AND BAROREFLEX IN RABBITS

Experiments were performed on 41 rabbits anesthetized with urethane, paralyzedwith flaxedil and ventilated artificially. Electrical shmulation of the pressor areaof the ventral surface of medulla oblongata (VSMp) elicited an increase in renalsympathetic nerve activity (RSNA) and arterial pressure (AP). Electrical stimula-tion of the aortic nerve (AN) induced sympathetic inhibition and fall of AP. Thesympatho-excitatory effect induced by VSMp stimulation persisted under thefollowing conditions: (1) VSMp and AN were stimulated simultaneously; (2)VSMp was stimulated during the stimulation of AN; (3) AN was stimulated duringthe stimulation of VSMp. In contrast, the sympatho-inhibitory effect induced byAN stimulation were greatly inhibited. It is suggested that the sympatho-excitatoryeffect of VSMp excitation can modulate the sympatho-inhibitory component ofthe baroreflex. The dynamic equilibrium between them is the basis for maintain-ing the resting level of AP.