Tetraethylammonium block of water flux in Aquaporin-1 channels expressed in kidney thin limbs of Henle's loop and a kidney-derived cell line.
Tetraethylammonium block of water flux in Aquaporin-1 channels expressed in kidney thin limbs of Henle's loop and a kidney-derived cell line.
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在亨利环的肾脏薄肢和肾脏衍生的细胞系中表达的水通道蛋白-1通道中水通量的四乙基铵块。
DOI：
10.1186/1472-6793-2-4
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Stamer, W Daniel
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文献类型：
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作者：
Yool, Andrea J;Brokl, Olga H;Pannabecker, Thomas L;Dantzler, William H;Stamer, W Daniel
水通道蛋白-1(Aquaporin-1，AQP1)通道是一种结构性的活性水通道，允许快速跨膜渗透水通量，同时也是一种环-GMP门控离子通道。四乙基氯化铵(TEA；0.05-10 mM)可以抑制非洲爪哇卵母细胞表达的人AQP1通道的渗透水通透性。本研究的目的是确定TEA是否阻断肾脏天然AQP1通道和重组AQP1通道在肾脏来源的MDCK细胞系中表达的渗透水通量。我们还证明了TEA不能抑制AQP1在卵母细胞中表达的依赖于cGMP的离子电导，支持水和离子通量涉及AQP1四聚体复合体中不同的药理途径的想法。TEA阻断了AQP1通道在肾脏和肾来源细胞中的透水性，表明这种作用并不局限于卵母细胞表达系统。在病毒介导的AQP1表达的MDCK细胞中，以及大量表达天然AQP1的大鼠肾脏Henle‘s环的下行细肢中，可以看到同样的抑制作用，但在不表达AQP1的上行细肢中则不存在。外部TEA(10 MM)不阻断依赖cGMP的AQP1的离子电导，用双电极电压钳在8BR-cGMP(10-50 mM)中预孵育后或在应用一氧化氮供体硝普钠(2-4 mM)时测量。TEA通过天然和异源表达的AQP1通道选择性地抑制渗透水通透性。AQP1中水和离子的途径对TEA的药理敏感性不同，与通道结构中独立的溶质途径的想法一致。这些结果证实了TEA作为分析AQP1功能的药理工具的有效性。
Aquaporin-1 (AQP1) channels are constitutively active water channels that allow rapid transmembrane osmotic water flux, and also serve as cyclic-GMP-gated ion channels. Tetraethylammonium chloride (TEA; 0.05 to 10 mM) was shown previously to inhibit the osmotic water permeability of human AQP1 channels expressed in Xenopus oocytes. The purpose of the present study was to determine if TEA blocks osmotic water flux of native AQP1 channels in kidney, and recombinant AQP1 channels expressed in a kidney derived MDCK cell line. We also demonstrate that TEA does not inhibit the cGMP-dependent ionic conductance of AQP1 expressed in oocytes, supporting the idea that water and ion fluxes involve pharmacologically distinct pathways in the AQP1 tetrameric complex. TEA blocked water permeability of AQP1 channels in kidney and kidney-derived cells, demonstrating this effect is not limited to the oocyte expression system. Equivalent inhibition is seen in MDCK cells with viral-mediated AQP1 expression, and in rat renal descending thin limbs of Henle's loops which abundantly express native AQP1, but not in ascending thin limbs which do not express AQP1. External TEA (10 mM) does not block the cGMP-dependent AQP1 ionic conductance, measured by two-electrode voltage clamp after pre-incubation of oocytes in 8Br-cGMP (10–50 mM) or during application of the nitric oxide donor, sodium nitroprusside (2–4 mM). TEA selectively inhibits osmotic water permeability through native and heterologously expressed AQP1 channels. The pathways for water and ions in AQP1 differ in pharmacological sensitivity to TEA, and are consistent with the idea of independent solute pathways within the channel structure. The results confirm the usefulness of TEA as a pharmacological tool for the analysis of AQP1 function.