Barron K W, Heesch C M
Department of Physiology and Biophysics, College of Medicine, University of Kentucky, Lexington 40536.
Am J Physiol. 1990 Sep;259(3 Pt 2):H720-7. doi: 10.1152/ajpheart.1990.259.3.H720.
The overall purpose of this study was to examine the effect of sinoaortic baroreceptor denervation (SAD) on the cardiovascular and sympathetic outflow responses to electrical stimulation of the posterior hypothalamus. In anesthetized rats that had undergone SAD 7-10 days before experimentation, electrical stimulation of the posterior hypothalamus elicited greater increases in mean arterial pressure, iliac vascular resistance, mesenteric vascular resistance, and lumbar sympathetic nerve activity than in sham-operated baroreceptor-intact animals. Similarly, the pressor effects of intravenous norepinephrine were also augmented in the baroreceptor-denervated group compared with the baroreceptor-intact group. When posterior hypothalamic and intravenous norepinephrine pressor stimuli, which produced equivalent pressor responses in sham-operated baroreceptor-intact animals, were compared in baroreceptor-denervated animals, the pressor effects of the central hypothalamic stimulus were enhanced to a greater degree than the norepinephrine pressor effects. These data provide evidence that arterial baroreceptor reflexes exert greater buffering of pressor stimuli initiated from the central nervous system compared with pressor responses due to peripheral vascular vasoconstrictor agents.
本研究的总体目的是研究去窦主动脉压力感受器（SAD）对心血管及交感神经传出反应的影响，该反应是针对下丘脑后部电刺激而言的。在实验前7 - 10天接受过SAD的麻醉大鼠中，下丘脑后部的电刺激引起的平均动脉压、髂血管阻力、肠系膜血管阻力和腰交感神经活动的增加幅度，比假手术的压力感受器完整动物更大。同样，与压力感受器完整组相比，去压力感受器组静脉注射去甲肾上腺素的升压作用也增强了。当在去压力感受器动物中比较下丘脑后部和静脉注射去甲肾上腺素的升压刺激（在假手术的压力感受器完整动物中产生等效的升压反应）时，下丘脑中央刺激的升压作用比去甲肾上腺素的升压作用增强程度更大。这些数据表明，与外周血管收缩剂引起的升压反应相比，动脉压力感受器反射对中枢神经系统引发的升压刺激具有更强的缓冲作用。
