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目的研究钩藤碱(Rhy)对颈动脉窦压力感受性反射(CSB)的作用并探讨其作用机制。方法利用隔离灌流大鼠颈动脉窦技术,确定各项功能参数,如阈压(TP)、饱和压(SP)、平衡压(EP)、工作范围(OR)、最大斜率(PS)和平均动脉压反射性下降幅度(RD)等。Rhy(10、50、100μmol/L)溶于K-H液后灌流窦区,以斜坡方式升降窦内压来观察Rhy对CSB的影响。分别预先灌流一氧化氮合酶抑制剂L-NAME,钾通道阻断剂四乙铵(TEA)和￡-型钙通道开放剂Bay K8644后再给予Rhy,观察它们对Rhy作用的影响。结果Rhy浓度依赖性地抑制了CSB,使其各功能参数改变,TP和SP增大,PS和RD均减小。Rhy的抑制作用不能被L-NAME(300μmol/L)和TEA(1 mmol/L)预处理所取消,而可被Bay K8644(500 nmol/L)明显减弱。结论Rhy抑制了CSB,此作用可能是通过减弱压力感受器的牵张敏感性离子通道的钙内流来实现,而与NO和钾通道无关。
Objective To study the effect of Rhyn on carotid sinus baroreflex (CSB) and its mechanism of action. Methods Peripheral carotid sinus technique was isolated and perfused to determine various functional parameters such as threshold pressure (TP), saturation pressure (SP), equilibrium pressure (EP), working range (OR), maximum slope (PS), and mean artery Pressure reflection decline (RD) and so on. Rhy (10, 50, 100 μmol/L) was dissolved in the K-H fluid and perfused in the sinus area. The effect of Rhy on the CSB was observed by ramping up the sinus pressure. Nitric oxide synthase inhibitor L-NAME was pre-perfused, and the potassium channel blocker tetraethylammonium (TEA) and the £-type calcium channel opener Bay K8644 were given to Rhy beforehand to observe their effect on Rhy. RESULTS Rhy inhibited CSB in a concentration-dependent manner, resulting in changes in its functional parameters, increased TP and SP, and decreased PS and RD. Rhy inhibition was not abrogated by pretreatment with L-NAME (300 μmol/L) and TEA (1 mmol/L) but was significantly attenuated by Bay K8644 (500 nmol/L). Conclusion Rhy inhibits CSB. This effect may be achieved by attenuating the calcium influx of stretch-sensitive ion channels in baroreceptors, but not with NO and potassium channels.