Inhibitory　effects　of　vinpocetine　on　sodium　current　in　rat　cardiomyocytes

目的：研究长春西汀对心肌细胞钠电流的作用．方法：用全细胞膜片箝技术记录大鼠心肌细胞钠电流．结果：长春西汀可逆性抑制心肌细胞钠电流的作用为剂量依赖性和电压依赖性，但未发现频率或使用依赖性．长春西汀１０－８０μｍｏｌ·Ｌ－１，对钠电流的抑制作用为１３％±２％至７５％±６％．半数抑制浓度ＩＣ５０值（９５％可信限）为３６４（２８１－４７１）μｍｏｌ·Ｌ－１．在膜电位以１０ｍＶ的间隔从－９０ｍＶ阶梯状去极化至＋４０ｍＶ时，抑制作用呈逐渐增加的趋势，约在０ｍＶ左右达到最大抑制．长春西汀对钠通道的稳态激活和失活过程的影响，可使钠窗电流（缓慢失活的钠电流）减少．

AIM: To study the effects of vinpocetine (Vin) on the sodium current ( I Na ) in cardiomyocytes. METHODS: The sodium current in adult rat ventricular myocytes was measured by whole cell patch clamp technique. RESULTS: The I Na in cardiomyocytes was blocked reversibly by Vin, in concentration dependent and voltage dependent manner, but not rate or use dependent. The I Na was attenuated by 13 %-75 % when the Vin concentration was raised from 10 to 80 μmol·L -1 . The IC 50 (95 % confidence limits) was 36.4 (28 1-47 1) μmol·L -1 . When the membrane potential depolarized over the range of -90 mV to +40 mV in 10 mV step, inhibitory effect of Vin on the I Na was 39 % at first, then maintained at a higher level, about 52 %±5 %. The maximal depression ( 57 % ) reached at about 0 mV. Vin influenced both the activation and inactivation processes of sodium channel, and resulted in attenuation of the window currents (the slowly inactivating sodium currents). CONCLUSION: Vin inhibited sodium currents in rat ventricular myocytes.