STEADY-STATE TTX-SENSITIVE (WINDOW) SODIUM CURRENT IN CARDIAC PURKINJE-FIBERS
STEADY-STATE TTX-SENSITIVE (WINDOW) SODIUM CURRENT IN CARDIAC PURKINJE-FIBERS
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DOI：
10.1007/bf00586939
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发表时间：
1979-01-01
影响因子：
4.5
通讯作者：
OJEDA, C
中科院分区：
文献类型：
--
作者：
ATTWELL, D;COHEN, I;OJEDA, C
对分离的绵羊浦肯野纤维的电压钳实验显示，在河豚毒素（TTX，3 μ g/ml）的存在下，在-65至-15 mV的电位范围内，稳态外向膜电流增加。10-5 M）。窗口电流被认为是快钠电流（INa）的稳态成分，由激活和失活曲线交叉产生，控制Na通道的开放。TTX对起搏电流IK 2（时间依赖性K电流）的反转电位、激活曲线、动力学和瞬时I-V关系无明显影响。在实验中发现的窗口延伸到动作电位平台范围内的电位。因此，稳态INa的微小变化可能对动作电位时程产生较大影响。TTX和局麻药的影响进行了讨论。
Voltage clamp experiments on isolated sheep Purkinje fibers showed an increase of the steady state outward membrane current, over the potential range -65 to -15 mV, in the presence of tetrodotoxin (TTX, 3 .cntdot. 10-5 M). The window current is considered to be the steady state component of the fast Na-current (INa), resulting from the crossover of the activation and inactivation curves which govern the opening of the Na channel. TTX had no significant effect of the reversal potential, activation curve, kinetics or instantaneous I-V relationship of the pacemaker current IK2 (time dependent K current). The window found in the experiments extends to potentials well into the range of the action potential plateau. Consequently small changes of the steady state INa might have large effects on the action potential duration. The effects of TTX and local anesthetics are discussed.