Increase in sensitivity of the baroreceptor reflex following microinjection of carbachol into the posterior hypothalamic nucleus of awake rats

C. R. Newey, J. R. Martin
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引用次数: 3

Abstract

  1. In a rat model, the baroreceptor reflex can be assessed by graded infusions of either phenylephrine or sodium nitroprusside with continuous hemodynamic monitoring.
  2. Microinjection of the cholinergic agonist carbachol (CCh) into the posterior hypothalamic nucleus (PHN) evokes an increase in mean arterial pressure and a change in heart rate. Lower doses of CCh evoke only tachycardia, whereas middle and higher doses evoke a biphasic change in heart rate of tachycardia followed by bradycardia.
  3. The bradycardia following the microinjection of CCh into the PHN can be attenuated by the previous administration of the vasopressin V1 receptor antagonist [d(CH2)5Tyr(Me)] arginine vasopressin (AVPX).
  4. Circulating arginine vasopressin (AVP) has been shown to increase the sensitivity of the baroreceptor reflex by stimulating vasopressin V1 receptors in the area postrema.
  5. The attenuation by AVPX of the bradycardia that results following the high doses of CCh suggests that AVP is released into the circulation following stimulation of cholinergic systems within the PHN.
  6. Thus, microinjection of a high dose of CCh (11 nmol) into the PHN alters the sensitivity of the baroreceptor reflex by increasing peripheral levels of AVP.
清醒大鼠下丘脑后核微量注射甲醇后压力感受器反射的敏感性增加
在大鼠模型中,压力感受器反射可通过分级输注苯肾上腺素或硝普钠并持续血流动力学监测来评估。向下丘脑后核(PHN)微量注射胆碱能激动剂恰巴醇(CCh)可引起平均动脉压升高和心率变化。低剂量的CCh只引起心动过速,而中剂量和高剂量的CCh引起心动过速和心动过缓的心率双相变化。在PHN内微量注射CCh后的心动过缓可通过先前给予抗利尿素V1受体拮抗剂[d(CH2)5Tyr(Me)]精氨酸抗利尿素(AVPX)来减轻。循环精氨酸抗利尿激素(AVP)通过刺激后脑区抗利尿激素V1受体增加压力感受器反射的敏感性。高剂量CCh引起的AVPX对心动过缓的衰减表明,在刺激PHN内的胆碱能系统后,AVP被释放到循环中。因此,向PHN微注射高剂量的CCh (11 nmol)通过增加外周AVP水平来改变压力感受器反射的敏感性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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