Song J, Jang Y Y, Shin Y K, Lee C, Chung S
Department of Pharmacology, Chung-Ang University, College of Medicine, 221 Heuk-Suk Dong, Dong-Jak Ku, Seoul, South Korea.
Brain Res. 2000 Feb 14;855(2):267-73. doi: 10.1016/s0006-8993(99)02405-1.
The effects of N-ethylmaleimide (NEM), an alkylating reagent to protein sulfhydryl groups, on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) sodium channels in rat dorsal root ganglion (DRG) neurons were studied using the whole cell configuration of patch-clamp technique. When currents were evoked by step depolarizations to 0 mV from a holding potential of -80 mV NEM decreased the amplitude of TTX-S sodium current, but exerted little or no effect on that of TTX-R sodium current. The inhibitory effect of NEM on TTX-S sodium channel was mainly due to the shift of the steady-state inactivation curve in the hyperpolarizing direction. NEM did not affect the voltage-dependence of the activation of TTX-S sodium channel. The steady-state inactivation curve for TTX-R sodium channel was shifted by NEM in the hyperpolarizing direction as that for TTX-S sodium channel. NEM caused a change in the voltage-dependence of the activation of TTX-R sodium channel unlike TTX-S sodium channel. After NEM treatment, the amplitudes of TTX-R sodium currents at test voltages below -10 mV were increased, but those at more positive voltages were not affected. This was explained by the shift in the conductance-voltage curve for TTX-R sodium channels in the hyperpolarizing direction after NEM treatment.
使用膜片钳技术的全细胞模式，研究了烷基化蛋白巯基的试剂N-乙基马来酰亚胺（NEM）对大鼠背根神经节（DRG）神经元中河豚毒素敏感（TTX-S）和河豚毒素抗性（TTX-R）钠通道的影响。当从-80 mV的 holding 电位通过阶跃去极化至0 mV诱发电流时，NEM降低了TTX-S钠电流的幅度，但对TTX-R钠电流的幅度几乎没有影响或没有影响。NEM对TTX-S钠通道的抑制作用主要是由于稳态失活曲线向超极化方向移动。NEM不影响TTX-S钠通道激活的电压依赖性。与TTX-S钠通道一样，NEM使TTX-R钠通道的稳态失活曲线向超极化方向移动。与TTX-S钠通道不同，NEM引起了TTX-R钠通道激活电压依赖性的变化。NEM处理后，在低于-10 mV的测试电压下TTX-R钠电流的幅度增加，但在更正电压下的幅度不受影响。这可以通过NEM处理后TTX-R钠通道的电导-电压曲线向超极化方向移动来解释。
