孤束核α受体调制脑室注射组胺对颈动脉窦反射的抑制  

α RECEPTORS IN THE NTS MODULATE DEPRESSION OF CAROTID BAROREFLEX INDUCED BY INTRACEREBROVENTRICULAR INJECTION OF HISTAMINE IN RATS

作　　者：王国卿[1] 宋军[1] 孙万平[1] 李金华[1] 周希平[1] 

机构地区：[1]苏州大学医学院基础医学系生理学教研室,江苏苏州215007

出　　处：《中国应用生理学杂志》2007年第1期57-61,共5页Chinese Journal of Applied Physiology

基　　金：苏州医学院科学技术项目基金资助课题(1995A-1)

摘　　要：目的:探讨孤束核(NTS)α1和α2受体在脑室注射(ICV)组胺(HA)对颈动脉窦反射(CBR)重调定中的作用。方法:孤离麻醉SD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ICV HA以及预先在NTS微量注射а1或а2受体拮抗剂对CBR的影响。结果:ICV HA(60μmol.L-1,5μl)导致ISP-MAP关系曲线后半程显著上移(P<0.05),ISP-增益关系曲线中部明显下移(P<0.05),反射参数MAP反射变动范围及反射最大增益减小(P<0.05);预先向NTS注射选择性的α1受体拮抗剂酚苄明(PBZ,3μmol.L-1,500 nl)或α2受体拮抗剂育亨宾(YOH,2.5μmol.L-1,500nl),均能明显加强HA的上述效应,PBZ的这种加强作用不如YOH的显著(P<0.05)。结论:脑室注射HA使CBR产生快速重调定,反射敏感性下降;NTS的α1、α2受体作用可减弱ICV HA对CBR的抑制性重调定;α2受体在调制这种重调定的过程中可能发挥更为重要的作用。Aim： To investigate the roles of α1 and a2 receptors in the nucleus tractus solitarius（NTS） in the carotid baroreflex（CBR） resetting induced by the intracerebroventricular injection（ICV） of histamine（HA）. Methods： The left and right carotid sinus regions were isolated from the systemic circulation in 25 Sprague-Dawley 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. The changes in CBR performance induced by ICV HA and the effects of pretreatment with α1 or α2 receptor antagonist into the NTS on the responses of CBR to HA were examined. Results： ICY HA（60 μmil· L^-1 in 5μl） significantly shifted the ISP-MAP relationship curve upwards（ P〈 0.05 ） and moved the middle part of ISP-C, ain relationship curve downwards（ P 〈 0.05）, and reduced the MAP range and maximum gain（ P 〈 0.05 ）. The pretreatment with phenoxybenzamine（PBZ, a selective antagonist of as receptor, 3 μmol· L^-1 in 500 nl） or yohimbine（ YOH, a selective antagonist of α2 receptor, 2.5 μmol· L^-1 in 500 nl） into the NTS could obviously intensify the above-mentioned changes in CBR performance inducedby HA, but the intensive effect of PBZ was less remarkable than that of YOH（P〈 0.05）. Conclusion： The intracere-broventrieular administration of HA results in a rapid resetting of CBR and a decrease in reflex sensitivity, and the functions of aI and receptors in the NTS might weaken CBR resetting induced by ICV HA. Furthermore, α2 receptor in the NTS might play an more important role in modulating the responses of CBR to HA.

关 键 词：颈动脉窦反射重调定 组胺 脑室注射 孤束核α1 α2受体 平均动脉压 

分 类 号：Q463[生物学—生理学] R331.3[医药卫生—人体生理学]