Potassium permeable channels in primary cultures of rabbit cortical collecting tubule.
Potassium permeable channels in primary cultures of rabbit cortical collecting tubule.
复制标题
兔皮质集合管原代培养物中的钾渗透通道。
DOI：
10.1038/ki.1991.231
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发表时间：
1991
影响因子：
19.6
通讯作者：
Eaton,DC
中科院分区：
文献类型：
--
作者：
Ling,BN;Hinton,CF;Eaton,DC
原代培养的家兔皮质集合小管钾离子通道。兔皮质集合小管（RCCT）原代培养物在含有1.5 µMaldosterone的可渗透胶原支持物上生长。在主细胞顶端膜的单一K+渗透通道进行了检查。在施加的贴片移液管电位（Vapp）从-60到+60 mV（细胞内部相对于移液管内部），外向电流（细胞到移液管）与8至10 pS的单位电导被视为在细胞附着（N = 31）和切除的内面向外（N = 15）的补丁。在静息膜电位（Vapp= 0 mV）下，0.75 mM BaCl 2暴露时，平均开放概率（Po= 0.85 ± 0.16）降低了50%。在细胞贴附的贴片中，第二种类型的外向电流仅在极端去极化时观察到，Vapp> +80 mV（N = 9）。通常在未施加电位的关闭状态（Po< 0.0005）下，该150 pS通道的Po随着去极化和/或胞质Ca 2+升高而显著增加。在计算的K+平衡电位为-84 mV的情况下，对于上述两种通道类型，切除的斑片反转电位< -50 mV，表明对K+的选择性高于Na+。在没有醛固酮的培养物中，很少观察到低电导K+通道，而盐皮质激素状态似乎不影响高电导K+通道频率。最后，一个30 pS的阳离子通道被发现是非选择性的K+ Na+，电压，细胞内Ca 2+或管腔Ba 2+不敏感。我们的结论是：1）来自醛固酮刺激的RCCT原代培养物的主细胞顶端膜含有（a）低电导、Ba 2+可降解的和（B）高电导、Ca 2 +/电压依赖性K+通道;和c）非选择性阳离子通道。2)低电导K+通道可能在天然RCCT盐皮质激素控制的K+分泌中发挥重要的生理作用，而后两种通道的功能尚不清楚，尽管类似的通道已被认为在细胞体积调节中发挥作用。
Potassium permeable channels in primary cultures of rabbit cortical collecting tubules. Rabbit cortical collecting tubule (RCCT) primary cultures, were grown on permeable, collagen supports with 1.5 µMaldosterone. Single K+permeable channels in principal cell apical membranes were examined. At applied patch pipette potential (Vapp) from -60 to +60 mV (cell interior with respect to pipette interior), outward currents (cell to pipette) with a unitary conductance of 8 to 10 pS were seen in cell-attached (N = 31) and excised inside-out (N = 15) patches. At resting membrane potential (Vapp= 0 mV), mean open probability (Po= 0.85 ± 0.16) decreased by 50% with 0.75 mMluminal BaCl2exposure. In cell-attached patches, a second type of outward current was seen only at extreme depolarization, Vapp> +80 mV (N = 9). Usually in the closed state (Po< 0.0005) at no applied potential, Pofor this 150 pS channel increased dramatically with depolarization and/or raising cytoplasmic Ca2+. With a calculated K+equilibrium potential of -84 mV, excised patch reversal potentials were < -50 mV for both the above channel types, indicating high selectivity for K+over Na+. In cultures grown without aldosterone low conductance K+channels were rarely observed, while mineralocorticoid status did not appear to affect high conductance K+channel frequency. Finally, a 30 pS cation channel was found to be nonselective for K+over Na+, and insensitive to voltage, intracellular Ca2+or luminal Ba2+. We conclude that: 1) Principal cell apical membranes from aldosterone-stimulated, RCCT primary cultures contain (a) low conductance, Ba2+-inhibitable and (b) high conductance, Ca2+/voltage-dependent K+channels; and c) nonselective cation channels. 2) The low conductance K+channel may play an important physiologic role in native RCCT mineralocorticoid-controlled K+secretion, while the latter two channels' functions are unknown, although similar channels have been suggested to play a role in cell volume regulation.