Some kinetic and steady-state properties of sodium channels after removal of inactivation.
Some kinetic and steady-state properties of sodium channels after removal of inactivation.
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DOI：
10.1085/jgp.77.1.1
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发表时间：
1981-01
期刊：
影响因子：
--
通讯作者：
Oxford GS
中科院分区：
文献类型：
--
作者：
Oxford GS
为了研究电压依赖性钠电导激活的动力学和稳态特性，鱿鱼巨轴突内部灌注链霉蛋白酶或N-溴乙酰胺和电压钳位。参数的激活，τ m和gNa（V），和失活，τ Na，进行了测量和比较，与那些从控制轴突的假设下，gNa oc m3 h的霍奇金-赫胥黎计划。从INa的开启获得的τ m（V）值与对照轴突和其他人先前的确定很好地一致。来自Na尾电流的tau Na（V）值也未被链霉蛋白酶处理改变，并且与先前公布的值相当匹配。在相同的电势下，从3 × tau Na（V）获得的tau m（V）比从INa导通获得的tau m（V）大得多，导致不连续的分布。稳态In（gNa/gNa最大值- gNa）与电压的关系不是线性的，并且具有5.3 mV/e倍gNa的极限对数斜率。电压阶跃程序，诱导第二次开启INa在各个阶段的失活（钠尾电流）过程中揭示准指数激活在早期阶段，变得越来越S形失活的进展。对于中度去极化，初级和次级活化动力学是可重叠的。这些数据表明，虽然m3可以描述INa开启的形状，但它不能定量地解释复极后gNa的动力学。动力学计划gNa中，大量的失活发生的独特的途径之间的导电和休息状态被证明是不可能的。看来，在线性动力学模型的活化的限速步骤可能是终端导电状态和相邻的非导电中间。
To study the kinetic and steady-state properties of voltage-dependent sodium conductance activation, squid giant axons were perfused internally with either pronase or N-bromoacetamide and voltage clamped. Parameters of activation, tau m and gNa(V), and deactivation, tau Na, were measured and compared with those obtained from control axons under the assumption that gNa oc m3h of the Hodgkin-Huxley scheme. tau m(V) values obtained from the turn-on of INa agree well with control axons and previous determinations by others. tau Na(V) values derived from Na tail currents were also unchanged by pronase treatment and matched fairly well previously published values. tau m(V) obtained from 3 x tau Na(V) were much larger than tau m(V) obtained from INa turn-on at the same potentials, resulting in a discontinuous distribution. Steady- state In (gNa/gNa max - gNa) vs. voltage was not linear and had a limiting logarithmic slope of 5.3 mV/e-fold gNa. Voltage step procedures that induce a second turn-on of INa during various stages of the deactivation (Na tail current) process reveal quasiexponential activation at early stages that becomes increasingly sigmoid as deactivation progresses. For moderate depolarizations, primary and secondary activation kinetics are superimposable. These data suggest that, although m3 can describe the shape of INa turn-on, it cannot quantitatively account for the kinetics of gNa after repolarization. Kinetic schemes for gNa in which substantial deactivation occurs by a unique pathway between conducting and resting states are shown to be unlikely. It appears that the rate-limiting step in linear kinetic models of activation may be between a terminal conducting state and the adjacent nonconducting intermediate.
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影响因子：
5.5
作者：
KEYNES, RD;ROJAS, E
通讯作者：
ROJAS, E
影响因子：
3.8
作者：
ARMSTRONG, CM;GILLY, WF
通讯作者：
GILLY, WF
影响因子：
5.5
作者：
KEYNES, RD;ROJAS, E
通讯作者：
ROJAS, E
影响因子：
5.5
作者：
HODGKIN, AL;HUXLEY, AF
通讯作者：
HUXLEY, AF
DOI：
10.1007/bfb0030498
发表时间：
1978-01-01
期刊：
Reviews of physiology, biochemistry and pharmacology
影响因子：
--
作者：
Almers, W
通讯作者：
Almers, W