A Na+‐activated K+ current in cultured brain stem neurones from chicks.
A Na+‐activated K+ current in cultured brain stem neurones from chicks.
复制标题
培养的雏鸡脑干神经元中存在 Na+ 激活的 K+ 电流。
DOI：
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
A. R. Martin
中科院分区：
文献类型：
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作者：
S. Dryer;J. T. Fujii;A. R. Martin
1. 采用膜片钳技术研究了从胚胎鸡脑干培养的神经元中Na+激活的K+电流（IK(Na)）的特性。2. 在全细胞箝位的情况下，去极化电压指令引起一个向内电流，然后是一个有两个分量的向外电流，第一个是瞬态电流，第二个是持续电流。3. 河豚毒素（TTX， 1微米）消除向内电流和向外电流的瞬态成分，不影响持续向外电流。此外，当外部Na+全部被Li+取代时，瞬态向外电流减弱，表明Na+进入细胞特异性激活。4. 用Li+溶液中得到的记录与Na+溶液中得到的记录相减，得到瞬态外向电流的时间过程。在向内电流的衰减和瞬态向外电流的开始之间有明显的重叠。5. 当瞬态向外电流达到峰值后，膜被逐步过渡到更高的超极化水平，尾部电流与计算出的K+平衡电位附近的电流反转极性相关。6. 4‐氨基吡啶（4‐AP, 4 mM）消除了瞬时外向电流和大约一半的持续晚期电流。四乙基铵（TEA, 2 mM）对瞬态电流没有影响，但对持续电流略有降低。7. 在LiCl洗浴液中制成的内外贴片含有通过将贴片的细胞质面暴露于Na+而激活的通道。只要Na+存在，通道活性就会持续。8. 单通道电流在K+平衡电位处反转，并与依赖于K+浓度的主电导相关（当[K+]o = 15 mM时约为50 pS， [K+]i = 5 mM时约为100 pS，当[K+]i增加到75 mM时）。9. 随着胞质Na+浓度的增加，通道的打开概率增加。在[Na+]i = 150 mM（测试的最大浓度）时，通道几乎连续打开。在50毫米时，打开概率要小得多，在20毫米时仍然可以测量。IK（Na）的大小及其与向内Na+电流的重叠表明，这些通道对动作电位的复极化阶段有重要贡献。此外，通道活性与Na+浓度之间的关系表明，在静息细胞内Na+浓度下，通道可能对膜电导做出可测量的贡献。
1. Patch‐clamp techniques were used to study the properties of a Na+‐activated K+ current (IK(Na) in neurones cultured from embryonic chick brain stem. 2. With whole‐cell clamp, a depolarizing voltage command evoked an inward current that was followed by an outward current with two components, the first transient, the second sustained. 3. Tetrodotoxin (TTX, 1 microM) eliminated the inward current and the transient component of the outward current, without affecting the sustained outward current. In addition, the transient outward current was attenuated when all external Na+ was replaced by Li+, suggesting that it was activated specifically by Na+ entry into the cell. 4. The time course of the transient outward current was obtained by subtracting records obtained in Li+ solution from those obtained in Na+ solution. There was significant overlap between the decay of the inward current and the onset of the transient outward current. 5. When just after the peak of the transient outward current, the membrane was stepped to progressively more hyperpolarized levels, the tail currents associated with the current reversed polarity near the calculated K+ equilibrium potential. 6. 4‐Aminopyridine (4‐AP, 4 mM) abolished the transient outward current and approximately half of the sustained late current. Tetraethylammonium (TEA, 2 mM) had no effect on the transient current, but reduced the sustained current slightly. 7. Inside‐out patches, made in LiCl bathing solutions, contained channels that were activated by exposing the cytoplasmic face of the patch to Na+. Channel activity continued as long as Na+ was present. 8. The single‐channel currents reversed at the K+ equilibrium potential, and were associated with a main conductance that depended upon K+ concentration (about 50 pS with [K+]o = 15 mM, [K+]i = 5 mM, and 100 pS when [K+]i was increased to 75 mM). 9. The open probability of the channels increased with increasing cytoplasmic Na+ concentration. At [Na+]i = 150 mM (the maximum concentration tested), channels were open almost continuously. Open probability was considerably less at 50 mM, and still measureable at 20 mM. 10. The magnitude of IK(Na) and its overlap with the inward Na+ current indicate that these channels contribute significantly to the repolarizing phase of the action potential. In addition, the relation between channel activity and Na+ concentration suggests that the channels may make a measurable contribution to membrane conductance at resting intracellular Na+ concentrations.
影响因子：
2.5
作者：
C. Stafstrom;P. Schwindt;M. C. Chubb;W. Crill
通讯作者：
C. Stafstrom;P. Schwindt;M. C. Chubb;W. Crill
体外猫感觉运动皮层神经元的缓慢电导及其在缓慢兴奋性变化中的作用。
影响因子：
2.5
作者：
Schwindt,PC;Spain,WJ;Foehring,RC;Chubb,MC;Crill,WE
通讯作者：
Crill,WE
来自 Edinger-Westphal 核的节前神经元：细胞培养中的生长和组织化学特征。
影响因子：
2.9
作者：
Fujii,JT;Berg,DK
通讯作者：
Berg,DK