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Effect of intracerebroventricular injection of histamine on carotid sinus baroreceptor reflex in anesthetized rats and its mechanism

Wang Guoqing, Zhou Xiping, Huang Weiqiu

Department of Physiology,Medical School,Soochow University.Suzhou 215007,Jiangsu

Abstract

The main results obtained are as follows. (1) i.c.v. injection of HA (100 ng) significantly shifted the ISP-MAP relationship curve upwards and moved the middle part ofo ISP-Gain relationship curve downwards, and reduced the MAP range and maximum gain (G_(max)), but increased the threshold pressure (TP), saturation pressure (SP) and ISP at G_(max) (ISP_(Gmax)). (2) The pretreatment with H_(1) or H_(2) receptors antagonist, chlorpheniramine (CHL, 5#mu#g) or cimetidine (CIM, 15#mu#g), could obviously diminish the above-mentioned changes in CSR performance induced by HA, but the effect of CIM was less remarkable than that of CHL. (3) The pretreatment with both CHL and CIM (5 #mu#g and 15 #mu#g) at the same time abolished the responses of CSR performance to HA completely. (4) After microinjection of CHL (0.5 #mu#g) or CIM (1.5 #mu#g) into the NTS, the responses of CSR to HA were similar to those after i. c. v. CHL or CIM, but the change in TP was significantly decreased.

Key words: Carotid sinus baroreceptor reflex;Histamine;Chlorpheniramine;Cimetidine;Intracerebreventricular injection;Nucleus of solitary tract;Mean arterial pressure

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Citing This Article：

Wang Guoqing, Zhou Xiping, Huang Weiqiu. Effect of intracerebroventricular injection of histamine on carotid sinus baroreceptor reflex in anesthetized rats and its mechanism. Acta Physiol Sin 2002; 54 (6): (in Chinese with English abstract).