IBTX及KT-5823在氯胺酮舒张大鼠离体气管平滑肌中的作用

目的:观察氯胺酮舒张大鼠离体气管平滑肌的作用与大电导钙激活钾通道(BKCa)及蛋白激酶G(PKG)信号传导系统的关系。方法:大鼠处死后,取主气管中段,分离气管周围的脂肪及疏松结缔组织,再剪成3~5mm的气管条,观察10-2mg/ml,10-1mg/ml,4×10-1mg/ml及10×10-1mg/ml的氯胺酮对乙酰胆碱预收缩后气管条张力的作用。然后用BKCa特异性阻断剂IBTX(3×10-6M)或PKG抑制剂KT-5823(2×10-6M)孵育气管条后,观察4×10-1mg/ml的氯胺酮对离体大鼠气管条的影响。结果:氯胺酮可以剂量依赖性舒张大鼠离体气管平滑肌;用IBTX或KT-5823孵育后,4×10-1mg/ml的氯胺酮引起的气管舒张作用减弱(P<0.05)。结论:氯胺酮对大鼠气管平滑肌呈剂量依赖性舒张作用;其舒张作用与氯胺酮激活PKG信号传导系统和BKCa有关。

Role of IBTX and KT-5823 in ketamine-induced dilation of isolated rat tracheal smooth muscle

Objective: To investigate the role of large conductance Ca2 +-activated-K+ channel(BKCa) and protein kinase G(PKG) signal pathway in ketamine-induced dilation of isolated rat tracheal smooth muscle.Methods : Rats were executed,after removal of surrounding connective tissue and fat,all tracheas were cut into strips of 3~5mm.The dilation effect of ketamine(10-2mg/ml,10-1mg/ml,4×10-1mg/ml and 10×10-1mg/ml) on the tracheal rings pre-constricted by acetylcholine(Ach) was studied.Tracheal strips pretreated with BKCa blocker(IBTX) or PKG blocker(KT-5823) were used to explore the effects of 4×10-1mg/ml ketamine on tracheal strips of rats.Results: ketamine relaxed tracheal rings in a dose dependent manner in rats(P<0.05).Pretreatment to the rings with IBTX(3×10-6M) or KT-5823(2×10-6M) decreased the relaxation effect of ketamine(4×10-1mg/ml),which was different compared with control group(P<0.05).Conclusion: Ketamine dilatated the isolated rat tracheal ring in a dose-dependent manner.The dilatation of ketamine in 4×10-1mg/ml to rat tracheal strips may be related to the activation of BKCa and PKG signal pathway.