Cl^--sensitive with-no-lysine kinase (WNK) plays a key role in regulating the thiazide-sensitive sodium-chloride cotransporter (NCC) in the distal convoluted tubule (DCT). Cl^- enters DCT cells through NCC and leaves the cell across the basolateral membrane via the Cl^- channel ClC-Kb or a K-Cl cotransporter (KCC). While KCC is electroneutral, Cl^- exit via ClC-Kb is electrogenic. Therefore, an alteration in DCT basolateral K⁺ channel activity is expected to influence Cl^- movement across the basolateral membrane. Although a role for intracellular Cl^- in the regulation of WNK and NCC has been established, intracellular Cl^- concentrations ([Cl^-]_i) have not been directly measured in mammalian DCT. Therefore, to measure [Cl^-]_i in DCT cells, we have generated a transgenic mouse model expressing an optogenetic kidney-specific Cl-Sensor and measured Cl^- fluorescent imaging in the isolated DCT. Basal measurements indicate that the mean [Cl^-]_i is approximately 7 mM. Stimulation of chloride exit with low chloride hypotonic solutions decreased [Cl^-]_i, whereas inhibition of KCC by DIOA or inhibition of ClC-Kb by NPPB increased [Cl^-]_i, suggesting roles for both KCC and ClC-Kb modulating [Cl^-]_i . Blocking the basolateral K⁺ channels, Kir4.1/5.1, with barium significantly increased the [Cl^-]_i. Finally, a decrease in extracellular K⁺ concentration transiently decreased [Cl^-]_i whereas raising extracellular K⁺ transiently increased [Cl^-]_i, further suggesting a role for Kir4.1/5.1 in the regulation of [Cl^-]_i. We conclude that the alteration in ClC-Kb, KCC and Kir4.1/5.1 activity influences the [Cl^-]_i in the DCT.

中文翻译：

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远曲小管 Cl- 浓度通过 K+ 通道和转运蛋白进行调节。

Cl ^-敏感的无赖氨酸激酶 (WNK) 在调节远曲小管 (DCT) 中噻嗪类敏感的氯化钠协同转运蛋白 (NCC) 中起关键作用。Cl ^-通过 NCC 进入 DCT 细胞，并通过 Cl ^-通道 ClC-Kb 或 K-Cl 协同转运蛋白 (KCC)离开细胞穿过基底外侧膜。虽然 KCC 是电中性的，但 Cl ^-通过 ClC-Kb 退出是生电的。因此，DCT 基底外侧 K ⁺通道活性的改变预计会影响 Cl ^-跨基底外侧膜的运动。尽管已确定细胞内 Cl ^-在 WNK 和 NCC 的调节中的作用，但细胞内 Cl ^-尚未在哺乳动物 DCT 中直接测量浓度 ([Cl ^- ] _i )。因此，为了测量DCT 细胞中的[Cl ^- ] _i，我们生成了一个表达光遗传学肾脏特异性 Cl 传感器的转基因小鼠模型，并在分离的 DCT 中测量了 Cl ^-荧光成像。基础测量值表明 [Cl ^- ] _i的平均值约为 7 mM。用低氯低渗溶液刺激氯化物排出降低了 [Cl ^- ] _i，而 DIOA 对 KCC 的抑制或 NPPB 对 ClC-Kb 的抑制增加了 [Cl ^- ] _i，表明 KCC 和 ClC-Kb 调节 [Cl ^- ] _{i 的作用}。用钡阻断基底外侧 K ⁺通道 Kir4.1/5.1，显着增加 [Cl ^- ] _i。最后，细胞外K ⁺浓度的降低瞬时降低[Cl ^- ] _{i ，}而升高细胞外K ⁺瞬时增加[Cl ^- ] _i，进一步表明Kir4.1/5.1 在调节[Cl ^- ] _{i 中的作用}。我们得出结论，ClC-Kb、KCC 和 Kir4.1/5.1 活性的改变会影响 [Cl ^- ] _i 在 DCT 中。