中枢内源性乙酰胆碱对颈动脉窦压力感受器反射的影响

目的探讨中枢内源性乙酰胆碱（ACh）对颈动脉窦压力感受器反射（CSR）的作用。方法 SD大鼠麻醉后孤离其双侧颈动脉窦区,将不同窦内压（ISP）与其对应的平均动脉压（MAP）值进行Logistic曲线方程拟合,求得ISP-MAP关系曲线及其反射特征参数,观察侧脑室注射不同剂量的拟胆碱药毒扁豆碱（PHY）对CSR的影响。结果侧脑室分别注射低（1.8 mmol/L）、中（3.6 mmol/L）、高（5.4 mmol/L）剂量的PHY可导致ISP-MAP关系曲线在ISP 120～280 mmHg区间明显依次上移（P〈0.05）,ISP-增益关系曲线中部明显依次下移（P〈0.05）,反射参数中调定点、阈压、饱和压和最大增益时的窦内压值明显增大（P〈0.05）,MAP反射变动范围及反射最大增益明显减小（P〈0.05）。结论 PHY引起中枢内源性ACh增多,对CSR具有抑制性重调定作用,且这种效应呈现明显的剂量依赖性。

Effects of the Central Endogenous Acetylcholine on Carotid Sinus Baroreceptor Reflex in Rats

Objective To investigate the role of the central endogenous acetylcholine（ACh） in modulating carotid sinus baroreceptor reflex（CSR）.Methods The left and right carotid sinus regions were isolated from the systemic circulation in 29 male Sprague-Dawley rats anesthetized with pentobarbital sodium.The intracarotid sinus pressure（ISP） was altered in a stepwise manner in vivo to trigger the CSR.ISP-mean arterial pressure（MAP） relationship curve and its characteristic parameters were constructed by fitting to the logistic function with five parameters.The effects of the intracerebroventricular physostigmine（PHY） with different doses on the changes in CSR performance were observed.Results Intracerebroventricular microinjection of PHY with respective dose 1.8,3.6 or 5.4 mmol/L significantly shifted the ISP-MAP relationship curve upwards in turn at ISP changes from 120~280 mmHg and the ISP-gain relationship curve downwards in order（P0.05）,and obviously increased the value of the reflex parameters such as the set point,threshold pressure,saturation pressure and ISP at maximum gain（P0.05）,but remarkably decreased the MAP range and maximum gain（P0.05）.Conclusion The increased release of the central endogenous ACh resulted from the intracerebroventricular microinjection of PHY,a cholinomimetic,induces a inhibitory resetting of the CSR which shows dose dependent.