兔近端直小管管腔膜中的钾通道。来自囊泡研究的证据。
Potassium channels in the luminal membrane of rabbit proximal straight tubule. Evidence from vesicle studies.
作者信息
Jacobsen C, Røigaard-Petersen H, Sheikh M I
机构信息
Institute of Medical Biochemistry, University of Aarhus, Denmark.
出版信息
Biochem J. 1989 Aug 15;262(1):271-5. doi: 10.1042/bj2620271.
The characteristics of 86Rb+ fluxes through K+ channels in luminal-membrane vesicles isolated from the pars recta of rabbit proximal tubule were studied. In KCl-loaded vesicles from the pars recta, transient accumulation of 86Rb+ is observed which is modestly inhibited by BaCl2 and blocked by CdCl2. The isotope accumulation is driven by an electrical diffusion potential, as shown in experiments using either these membrane vesicles loaded with different anions, or an outwardly directed Li+ gradient with a Li+ ionophore. The vesicles containing the channel show a cation selectivity with the order K+ greater than Rb+ greater than choline+ greater than or equal to Li+ greater than Na+. The CdCl2-sensitive 86Rb+ flux is dependent on intravesicular Ca2+. Increasing concentrations of Ca2+ gradually decreased the 86Rb+ uptake and at 1 microM-Ca2+ the CdCl2-sensitive isotope flux is nearly abolished.
研究了从兔近端小管直部分离的管腔膜囊泡中通过钾通道的⁸⁶Rb⁺通量的特性。在来自直部的加载氯化钾的囊泡中，观察到⁸⁶Rb⁺的瞬时积累，其受到氯化钡的适度抑制并被氯化镉阻断。同位素积累由电扩散电位驱动，如使用加载不同阴离子的这些膜囊泡或带有锂离子载体的外向锂梯度的实验所示。含有该通道的囊泡表现出阳离子选择性，顺序为K⁺＞Rb⁺＞胆碱⁺≥Li⁺＞Na⁺。对氯化镉敏感的⁸⁶Rb⁺通量依赖于囊泡内的Ca²⁺。Ca²⁺浓度增加逐渐降低⁸⁶Rb⁺摄取，在1微摩尔Ca²⁺时，对氯化镉敏感的同位素通量几乎被消除。
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