中文摘要：

目的观察KCNQ2／3通道电流特征及M1受体激活对该电流的调节作用．方法以CHO细胞作为表达体系，用脂质体共转染KCNQ2、KCNQ3钾离子通道及毒蕈碱型M1受体。全细胞膜片钳方法，观察KCNQ2／3电流特征，药理学阻断剂的作用及M1受体激活对电流的调节。结果KC—NQ2／3电流呈现慢激活、低阈值、非失活、电压依赖性的外向钾离子电流特点，其激活电压的阈值在-60mV，半数激活电压值（-26．8±1．2）mV，其去活曲线可用双指数方程拟合，Tfast约101 ms；Tslow约为309ms．该电流对4-AP，Ba^2＋,TEA不敏感，Linopirdine抑制KCNQ2／3电流IC50为（6．5±0．83）μmol·L^-1。乙酰胆碱激活M1受体后会可逆性地抑制KCNQ2／3电流，其抑制的IC50为（0．7±0．05）μmol·L^-1。结论KCNQ2／3通道作为神经细胞M通道的分子基础，其电流特征与M电流一致，Linopirdine对其有较强阻断作用，神经递质乙酰胆碱通过激活M1受体明显抑制该通道电流。研究KCNQ2／3通道电流特征及受体调节规律，对于理解与中枢兴奋性有关的疾病如：惊厥、癫痫、阿尔采末病等发生机制有重要指导意义．

英文摘要：

Aim To study the characteristics of KCNQ2/3 potassium channel expressed in CHO cells and its modulation by M1 receptor. Methods KCNQ2 and KCNQ3 potassium channels and M1 receptor were coexpressed in CHO cells. Whole cell patch-clamp techniques was used to observe the characteristics of KCNQ2/3 current,its modulation by the M1 receptor, and the effects of the common potassium channel blockers. Results KCNQ2/3 current recorded in CHO cells was a slow-activation low-threshold non-inactivating, voltage-dependent outward potassium current. KCNQ2/3 current was elicited at about -60 mV, V1/2 （ -26.8±1.2） mV and the deactivation current fitted two exponential function, with Tfast, of 101ms and Tslow of 309 ms. The channel was not sensitive to common pharmacological blockers such as 4-AP, Ba^2＋ and TEA, but was inhibited significantly by linopirdine ,with a IC50 of （6. 5 ± 0. 83 ）μmol·L^-1. Acetylcholine suppressed the KCNQ2/3 current reversibly via M1 receptor, with aICs0 of （0.7 ±0.05）μmol·L^-1 Conclusion KCNQ2 and KCNQ3 channels are the molecular basis of M-current observed in neuronal ceils. KCNQ2/Q3 current expressed in CHO ceils has similar characteristics as that seen in neuronal M-current. Linopirdine is a powerful blocker of KCNQ2/3 channel and acetylcholine inhibits the current by muscarinic M1 receptor. This experiment has laid a solid basis for further study of M-current and KCNQ2/3 current, and is important for the study of neurological diseases relating to alteration of M-current, such as convulsion, epilepsy and Alzheimers disease.