Transient potassium currents in avian sensory neurons.
Transient potassium currents in avian sensory neurons.
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鸟类感觉神经元中的瞬时钾电流。
DOI：
10.1152/jn.1990.63.4.725
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发表时间：
1990
影响因子：
2.5
通讯作者：
Kenyon,JL
中科院分区：
文献类型：
--
作者：
Florio,SK;Westbrook,CD;Vasko,MR;Bauer,RJ;Kenyon,JL
1.应用膜片钳技术研究了新鲜分散培养的鸡背根神经节(DRG)细胞电压激活的瞬时钾电流。在适宜记录钾电流的条件下，记录全细胞和细胞附着的膜片电流。2.在全细胞实验中，从正常静息电位(-50 mV到-70 mV)进行100ms的去极化引起持续的外向电流，该电流在几秒钟的时间尺度上失活。我们将这种现象归因于延迟整流电流的一个分量。在将超极化电位限制为负-80 mV后，去极化引起瞬时外向电流分量，这种电流分量随时间常数在8-26ms的范围内失活。我们将这种行为归因于瞬时外向电流分量。3.条件性超极化增加了净外向电流的激活速度，这意味着瞬时外向电流失活的消除允许它在从负电位去极化的过程中贡献早期的外向电流。4.瞬时电流在细胞分散当天更为显著，且随培养时间的延长而减小。5.在细胞贴附性斑块中，可观察到介导外向电流的单通道，该通道在静息时不活跃，但在去极化至-30 mV时瞬时激活。信道打开的概率迅速增加(在大约6毫秒内达到峰值)，然后随着时间常数在13-30毫秒的范围内下降。以钠为主要胞外阳离子时，单通道电导范围为18~32ps。以钾离子为主要胞外阳离子时，单通道电导约为43ps，通道电流在0 mV附近反转，与钾电流的预期相同。6.我们认为在全细胞实验中，瞬时钾通道参与了瞬时外向电流成分的调节。在正常静息电位的去极化过程中，这一电流是净电流的一个相对较小的分量，但在超极化电位去极化的早期，它可以贡献相当大的外向电流。
1. We used the patch-clamp technique to study voltage-activated transient potassium currents in freshly dispersed and cultured chick dorsal root ganglion (DRG) cells. Whole-cell and cell-attached patch currents were recorded under conditions appropriate for recording potassium currents. 2. In whole-cell experiments, 100-ms depolarizations from normal resting potentials (-50 to -70 mV) elicited sustained outward currents that inactivated over a time scale of seconds. We attribute this behavior to a component of delayed rectifier current. After conditioning hyperpolarizations to potentials negative to -80 mV, depolarizations elicited transient outward current components that inactivated with time constants in the range of 8-26 ms. We attribute this behavior to a transient outward current component. 3. Conditioning hyperpolarizations increased the rate of activation of the net outward current implying that the removal of inactivation of the transient outward current allows it to contribute to early outward current during depolarizations from negative potentials. 4. Transient current was more prominent on the day the cells were dispersed and decreased with time in culture. 5. In cell-attached patches, single channels mediating outward currents were observed that were inactive at resting potentials but were active transiently during depolarizations to potentials positive to -30 mV. The probability of channels being open increased rapidly (peaking within approximately 6 ms) and then declined with a time constant in the range of 13-30 ms. With sodium as the main extracellular cation, single-channel conductances ranged from 18 to 32 pS. With potassium as the main extracellular cation, the single-channel conductance was approximately 43 pS, and the channel current reversed near 0 mV, as expected for a potassium current. 6. We conclude that the transient potassium channels mediate the component of transient outward current seen in the whole-cell experiments. This current is a relatively small component of the net current during depolarizations from normal resting potentials, but it can contribute significant outward current early in depolarizations from hyperpolarized potentials.