TEMPORAL AND STEADY-STATE RELATIONSHIPS BETWEEN ACTIVATION OF SODIUM CONDUCTANCE AND MOVEMENT OF GATING PARTICLES IN SQUID GIANT-AXON
TEMPORAL AND STEADY-STATE RELATIONSHIPS BETWEEN ACTIVATION OF SODIUM CONDUCTANCE AND MOVEMENT OF GATING PARTICLES IN SQUID GIANT-AXON
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DOI：
10.1113/jphysiol.1976.sp011274
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发表时间：
1976-01-01
影响因子：
5.5
通讯作者：
ROJAS, E
中科院分区：
文献类型：
--
作者：
KEYNES, RD;ROJAS, E
1. 本文比较了在氟化铯灌注并保持高膜保持电位的鱿鱼巨轴突中，钠电导变化和钠门控电流的动力学和稳态特性。电导测量是在减少外部钠和尽可能多的电补偿的情况下进行的，以尽量减少由串联电阻引起的误差。2. 在初始延迟10 - 150 μ m（其大小是保持电位和脉冲幅度的函数）后，电导在去极化时的上升遵循立方体定律动力学。3. 由Hodgkin & Huxley （1952b）定义的时间常数taum值在‐140和+70 mV之间的膜电位范围内测定。它们位于一个几乎对称的钟形曲线上，在- 36毫伏时，最大（在6 - 3摄氏度时）刚好低于500毫伏。在相同的电位范围内，门控电流时间常数tau(V)的值被确定，并且发现位于非常相似的钟形曲线上。计算出的最小二乘最佳拟合最大值为460毫伏，也下降到约- 36毫伏。最小值曲线的中点位于‐34 mV，其斜率为0‐0139 mV‐1。对完整轴突的另一系列测量结果显示中电位为- 25 mV。在灌注轴突中，用常场方程比用gNa更能描述膜的状态。从PNa重新计算的最小值使曲线向正方向移动了约15mv。
1. Comparisons were made between the kinetics and steady‐state properties of the sodium conductance changes and of the sodium gating currents, in the squid giant axon perfused with caesium fluoride and maintained at a high membrane holding potential. The conductance measurements were made with reduced external sodium and as much electrical compensation as possible, in order to minimize errors caused by the series resistance. 2. After an initial delay of 10‐150 musec whose size was a function of the holding potential and pulse amplitude, the conductance rise on depolarization followed cube law kinetics. 3. Values of the time constant taum, as defined by Hodgkin & Huxley (1952b), were determined for membrane potentials ranging between ‐140 and +70 mV. They lay on a nearly symmetrical bell‐shaped curve with maximum (at 6‐3 degrees C) of just under 500 musec at ‐36 mV. 4. Values of the gating current time constant tau(V) were determined over the same potential range, and found to lie on a very similar bell‐shaped curve. A computed least‐squares best fit gave the maximum as 460 musec, also falling at about ‐36 mV. 5. The midpoint of the minfinity curve lay at ‐34 mV, and its slope at this point was 0‐0139 mV‐1. Another series of measurements on intact axons gave a midpotential of ‐25 mV. In the perfused axons the state of the membrane was better described by the constant field equation than by gNa. Recalculation of minfinity from PNa shifted the curve about 15 mV in a positive direction.