VOLTAGE CLAMP EXPERIMENTS ON INTERNALLY PERFUSED GIANT AXONS
VOLTAGE CLAMP EXPERIMENTS ON INTERNALLY PERFUSED GIANT AXONS
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DOI：
10.1113/jphysiol.1965.sp007732
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发表时间：
1965-01-01
影响因子：
5.5
通讯作者：
MEVES, H
中科院分区：
文献类型：
--
作者：
CHANDLER, WK;MEVES, H
电压钳实验进行了内部灌流的巨大轴突。早期外向电流观察到大的去极化与KCl+蔗糖（无钠）内的纤维和钠或胆碱人工海水外。这些电流与通常与Na离子运动相关的电流相似。当用RbCl、CsCl或蔗糖代替内部KCl时，它们降低。早期外向电流被打开，并以与早期钠电导定量相似的方式失活。钾可以通过钠通道，但比钠容易得多。通过降低内部pH值、用硫酸盐代替氯化物或变质，相对Na：K选择性没有改变;通过用蔗糖稀释内部KCl，选择性似乎降低。用NaCl替换内部KCl以与选择性PNa/pK = 12的钠电极一致的方式改变了早期电流的平衡电势。平衡电位测量与外部锂和内部铷和铯;阳离子的选择性遵循顺序Li [>] Na [>] Rb [>] Cs。假设只有一价阳离子通过钠通道，Li：Na：K：Rb：Cs的相对渗透率为1.1：1/12：1/40：1/61。更换内部钾与胆碱，钠，铷或铯降低晚电流低于预期的值从独立性原则。
Voltage clamp experiments were carried out on internally perfused giant axons. Early outward currents were observed with large depolarizations with KC1 + sucrose (no Na) inside the fibre and either sodium or choline artificial sea water outside. These currents were similar to those generally associated with movement of Na ions. They were decreased when the internal KC1 was replaced with RbCl, CsCl or sucrose. The early outward current was turned on and was inactivated in a manner quantitatively similar to that for the early sodium conductance. Potassium can go through the sodium channel but much less readily than sodium. The relative Na:K selectivity was not changed by lowering internal pH, by replacing chloride with sulphate or deterioration; the selectivity appeared to be lowered by diluting the internal KC1 with sucrose. Replacement of internal KC1 with Nacl changed the equilibrium potential of the early current in a manner consistent with a sodium electrode of selectivity PNa/pK = 12. Equilibrium potentials were measured with external lithium and with internal rubidium and caesium; the selectivity to cations followed the sequence Li [>] Na [>] Rb[>] Cs. On the assumption that only monovalent cations go through the sodium channel the relative permeabilities of Li:Na:K:Rb:Cs were 1.1:1/12:1/40:1/61. Replacement of internal potassium with either choline, sodium, rubidium or cesium decreased the late currents below the values expected from the independence principle.