SLOWLY ACTIVATING VOLTAGE-DEPENDENT K+ CONDUCTANCE IS APICAL PATHWAY FOR K+ SECRETION IN VESTIBULAR DARK CELLS
SLOWLY ACTIVATING VOLTAGE-DEPENDENT K+ CONDUCTANCE IS APICAL PATHWAY FOR K+ SECRETION IN VESTIBULAR DARK CELLS
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DOI：
10.1152/ajpcell.1994.267.3.c857
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发表时间：
1994-09-01
影响因子：
--
通讯作者：
SHEN, ZJ
中科院分区：
文献类型：
--
作者：
MARCUS, DC;SHEN, ZJ
Dark cell epithelium secretes K+ into the lumen of the vestibular labyrinth by a previously unidentified apical transport mechanism. Previous single-channel patch-clamp studies demonstrated nonselective cation channels and maxi-K+ channels in the apical membrane, but in too low a density to account for transepithelial K+ transport. In this report, we demonstrated with the cell-attached macro-patch-clamp technique an outward apical membrane current at 0-mV pipette voltage, which was stimulated by elevating bath K+ concentration from 3.6 to 25 mM and inhibited by 10 mu M bumetanide, similar to their known effects on transepithelial short-circuit current and K+ secretion. Furthermore, the patch current was activated over several seconds by a sustained depolarization and deactivated over several hundred milliseconds by a hyperpolarization. Current-voltage relationships from tail currents were obtained with either NaCl or KCl in the pipette. Depolarization from -40 to +40 mV led to an increased conductance by a factor of 7.3 +/- 1.7 (n = 7) and 19.2 +/- 7.6 (n = 6) for NaCl and KCl, respectively, and to a reversal voltage near the presumed equilibrium potential for K+. The results demonstrate that dark cell K+ secretion occurs via K+-selective channels with characteristics similar to those associated with the I-sK protein.
