Anion and cation permeability of a chloride channel in rat hippocampal neurons.
Anion and cation permeability of a chloride channel in rat hippocampal neurons.
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DOI：
10.1085/jgp.90.4.453
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发表时间：
1987-10
期刊：
影响因子：
--
通讯作者：
Nonner W
中科院分区：
文献类型：
--
作者：
Franciolini F;Nonner W
用膜片钳法研究了大鼠海马神经元电压依赖性Cl通道的离子渗透性。在对称的150 mM NaCl盐水中，该通道的单电导约为30 pS。根据Goldman-Hodgkin-Katz电压方程解释的反转电位表明，在存在盐梯度的条件下，Cl:Na渗透率比约为5:1。有许多阴离子存在；渗透率一般遵循溶性顺序。渗透阳离子包括Li， Na， K和Cs。当NaCl浓度高达1 m时，单一电导不饱和，当阴离子Cl被非均匀阴离子SO4取代时，没有观察到Na电流。单一电导取决于存在的阳离子种类。胞外锌或9-蒽羧酸可可逆地阻断该通道。Ca或Mg的生理浓度不影响Na:Cl渗透率比。通道的渗透性与渗透机制一致，该渗透机制涉及阴离子位点、外部阳离子和外部阴离子的活化复合物。
The ionic permeability of a voltage-dependent Cl channel of rat hippocampal neurons was studied with the patch-clamp method. The unitary conductance of this channel was approximately 30 pS in symmetrical 150 mM NaCl saline. Reversal potentials interpreted in terms of the Goldman-Hodgkin-Katz voltage equation indicate a Cl:Na permeability ratio of approximately 5:1 for conditions where there is a salt gradient. Many anions are permeant; permeability generally follows a lyotropic sequence. Permeant cations include Li, Na, K, and Cs. The unitary conductance does not saturate for NaCl concentrations up to 1 M. No Na current is observed when the anion Cl is replaced by the impermeant anion SO4. Unitary conductance depends on the cation species present. The channel is reversibly blocked by extracellular Zn or 9- anthracene carboxylic acid. Physiological concentrations of Ca or Mg do not affect the Na:Cl permeability ratio. The permeability properties of the channel are consistent with a permeation mechanism that involves an activated complex of an anionic site, an extrinsic cation, and an extrinsic anion.