Miniature endplate currents, endplate current fluctuations ("membrane noise"), and voltage-jump current relaxations were studied in voltage-clamped frog muscle fibers during decamethonium action. All three types of experiments revealed two kinetic processes controlling the opening of endplate channels, one that reflects agonist action and another that reflects local anesthetic-like blocking activity. The kinetic constants for these two steps were evaluated from measurements of the fast and slow time constants as a function of decamethonium concentration. At -130 mV membrane potential and 13 degrees, the mean open time of decamethonium-activated channels is 2.8 msec. The forward and backward rate constants for channel blocking are 1.7 X 10(7) M-1 sec-1 and 10(3) sec-1. The voltage dependencies of the channel lifetime and of the blocking equilibrium are similar to those seen with pure agonists and local anesthetics, respectively.
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机译：在十甲铵作用期间，在电压钳制的青蛙肌肉纤维中研究了微型终板电流，终板电流波动（“膜噪声”）和跳压电流松弛。所有这三种类型的实验都揭示了控制端板通道打开的两个动力学过程，一个反映了激动剂的作用，另一个反映了局部麻醉剂样的阻断活性。这两个步骤的动力学常数是根据快和慢时间常数的测量值（十甲铵浓度的函数）进行评估的。在-130 mV的膜电位和13度的条件下，十甲基铵激活的通道的平均打开时间为2.8毫秒。信道阻塞的前向和后向速率常数为1.7 X 10（7）M-1 sec-1和10（3）sec-1。通道寿命和阻断平衡的电压依赖性分别类似于纯激动剂和局部麻醉剂。
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