Potassium current activated by intracellular sodium in quail trigeminal ganglion neurons.
Potassium current activated by intracellular sodium in quail trigeminal ganglion neurons.
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DOI：
10.1085/jgp.95.5.961
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发表时间：
1990-05
期刊：
影响因子：
--
通讯作者：
Bader CR
中科院分区：
文献类型：
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作者：
Haimann C;Bernheim L;Bertrand D;Bader CR
采用全细胞电压钳和单通道记录技术研究了鹌鹑胚胎三叉神经节神经元的钠激活钾电流（KNa）。当KNa在电压钳中被阶跃去极化激活时，在INa和ENa阈值之间的所有电压下，KNa和INa之间存在比例关系。单通道记录表明，KNa可以被激活已经由12 mM的细胞内钠，并在50 mM的钠几乎完全激活。100 mM锂、100 mM胆碱或5 μ M钙不能激活KNa。通道开放的概率（Po）与钠浓度之间的关系以及KNa开放时间分布与钠浓度之间的关系表明，在KNa通道开放之前，两到三个钠离子协同结合。KNa通道对去极化敏感;在12 mM钠时，42 mV去极化导致Po增加e倍。在生理条件下，KNa通道的电导为50 pS。当细胞内和细胞外钾浓度分别为75和150 mM时，这种电导增加到174 pS。
Whole-cell voltage clamp and single-channel recordings were performed on cultured trigeminal ganglion neurons from quail embryos in order to study a sodium-activated potassium current (KNa). When KNa was activated by a step depolarization in voltage clamp, there was a proportionality between KNa and INa at all voltages between the threshold of INa and ENa. Single-channel recordings indicated that KNa could be activated already by 12 mM intracellular sodium and was almost fully activated at 50 mM sodium. 100 mM lithium, 100 mM choline, or 5 microM calcium did not activate KNa. The relationship between the probability for the channel to be open (Po) vs. the sodium concentration and the relationship of KNa open time-distributions vs. the sodium concentration suggest that two to three sodium ions bind cooperatively before KNa channels open. KNa channels were sensitive to depolarization; at 12 mM sodium, a 42-mV depolarization caused an e- fold increase in Po. Under physiological conditions, the conductance of the KNa channel was 50 pS. This conductance increased to 174 pS when the intra- and extracellular potassium concentrations were 75 and 150 mM, respectively.