摘要
目的 :探讨孤束核 (NTS)组胺 (HA)受体在脑室注射 (ICV)HA对颈动脉窦压力感受性反射 (CBR)影响中的作用。方法 :分离麻醉大鼠的双侧颈动脉窦区 ,将不同窦内压 (ISP)与其对应的平均动脉压 (MAP)值进行Logistic五参数曲线拟合 ,求得ISP MAP关系曲线及其特征参数 ,观察ICVHA以及预先在NTS微量注射HA受体拮抗剂对CBR的作用。结果 :ICVHA (10 0ng)导致ISP MAP关系曲线显著上移 ,ISP和增益关系曲线中部明显下移 ,反射参数中阈压、饱和压和最大增益时的窦内压值增大 ,MAP反射变动范围及反射最大增益减小。预先向NTS内注射H1或H2 受体拮抗剂氯苯吡胺 (CHL ,0 .5 μg)或西咪替丁 (CIM ,1.5 μg) ,均可明显减弱HA的上述效应 ,CIM的这种减弱作用不如CHL的显著。结论 :脑室给HA使CBR产生快速重调定 ,反射敏感性下降 ,NTS的H1和H2 受体尤以H1受体在ICVHA抑制CBR的机制中发挥重要作用 ,下丘脑
Aim: To explore the role of histaminergic receptors in the nucleus tractus solitarius(NTS) in the responses of carotid baroreflex(CBR) performance to the intracerebroventricular(ICV) injection of histamine(HA). Methods: The left and right carotid sinus regions were isolated from the systemic circulation in 18 Wistar rats anesthetized with pentobarbital sodium. The intracarotid sinus pressure(ISP) was altered in a stepwise manner. ISP-mean arterial pressure(MAP) relationship curve and its characteristic parameters were constructed by fitting to the logistic function with five parameters. We observed the changes in CBR performance induced by ICV HA and the effects of pretreatment with HA receptors antagonists into the NTS on the responses of CBR to HA. Results: ICV injection of HA(100 ng) significantly shifted the ISP-MAP relationship curve upwards and moved the middle part of 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)). The pretreatment with H_1 or H_2 receptors antagonist, chlorpheniramine(CHL, 0.5 μg) or cimetidine(CIM, 1.5 μg) into the NTS, could obviously diminish the above-mentioned changes in CBR performance induced by HA, but the effect of CIM was less remarkable than that of CHL. Conclusion: The intracerebroventricular administration of HA results in a rapid resetting of CBR and a decrease in reflex sensitivity, and the histaminergic receptors in the NTS (H_1 and H_2 receptors), especially H_1 receptors might play an important role in the responses of CBR to HA, and furthermore, the effects of the central HA on CBR might be related to a histaminergic descending pathway from the hypothalamus to NTS.
出处
《中国应用生理学杂志》
CAS
CSCD
北大核心
2004年第3期285-289,共5页
Chinese Journal of Applied Physiology
