Jdaïâa H, Guilbault P
Gen Physiol Biophys. 1986 Feb;5(1):3-16.
Two inward currents were observed in crayfish muscle membrane during depolarization steps by the method described by Adrian et al. (1970). Under voltage clamp conditions, hyperpolarization steps elicited a large current (leak current If), associated with an inward voltage dependent current. This inward current was inhibited by niflumic acid (NA), a drug known to block Cl---HCO-3 exchange (Cousin et Motais 1982; Brûlè et al. 1983b). Dynamic outward currents triggered by depolarizing steps were inhibited to a great extent by TEA, the not inhibited portion disappearing when procaine (2 mmol/l) was added to external solution. In the presence of TEA, procaine and NA, it was thus possible to dissect the regenerative calcium current (ICa) into two components: a "fast component" (ICa1) and a "slow component" (ICa2). The reversal potential of ICa was 65 mV (for [Ca]0 = 2.8 mmol/l), and [Ca]i could be calculated to be 1.6 X 10(-5) mol/l. This value of [Ca]i is the same as calculated from values reported by Hencek and Zachar (1977). ICa1 was triggered at a threshold membrane potential of -45 mV and ICa2 at -30 mV. Moreover, the inactivation kinetics for ICa1 was faster than that for ICa2. Our results are in perfect agreement with those obtained by Zahradník and Zachar (1982) who postulated two populations of calcium channels.
采用阿德里安等人（1970年）所描述的方法，在小龙虾肌肉膜去极化过程中观察到两种内向电流。在电压钳制条件下，超极化过程引发了一个大电流（漏电流If），这与一个内向电压依赖性电流相关。这种内向电流被尼氟灭酸（NA）抑制，尼氟灭酸是一种已知能阻断Cl---HCO-3交换的药物（库辛和莫泰斯，1982年；布鲁勒等人，1983年b）。去极化过程触发的动态外向电流在很大程度上被TEA抑制，当向外部溶液中加入普鲁卡因（2 mmol/l）时，未被抑制的部分消失。因此，在存在TEA、普鲁卡因和NA的情况下，有可能将再生钙电流（ICa）分解为两个成分：一个“快速成分”（ICa1）和一个“慢速成分”（ICa2）。ICa的反转电位为65 mV（对于[Ca]0 = 2.8 mmol/l），[Ca]i可计算为1.6×10(-5) mol/l。这个[Ca]i值与亨内克和扎哈尔（1977年）报道的值计算出的结果相同。ICa1在膜电位阈值为-45 mV时触发，ICa2在-30 mV时触发。此外，ICa1的失活动力学比ICa2快。我们的结果与扎赫拉德尼克和扎哈尔（1982年）的结果完全一致，他们推测存在两种钙通道群体。
