Greenlee Megan M, Mitzelfelt Jeremiah D, Duke Billie Jeanne, Al-Khalili Otor, Bao Hui-Fang, Eaton Douglas C
Department of Physiology, Emory University School of Medicine, Atlanta, Georgia.
Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
Am J Physiol Renal Physiol. 2015 Apr 1;308(7):F697-705. doi: 10.1152/ajprenal.00270.2014. Epub 2015 Jan 13.
Many hormonal pathways contribute to the regulation of renal epithelial sodium channel (ENaC) function, a key process for maintaining blood volume and controlling blood pressure. In the present study, we examined whether the peptide hormone prolactin (PRL) regulates ENaC function in renal epithelial cells (A6). Basolateral application of several different concentrations of PRL dramatically stimulated the transepithelial current in A6 cells, increasing both amiloride-sensitive (ENaC) and amiloride-insensitive currents. Using cell-attached patch clamp, we determined that PRL increased both the number (N) and open probability (Po) of ENaC present in the apical membrane. Inhibition of PKA with H-89 abolished the effect of PRL on amiloride-sensitive and insensitive transepithelial currents and eliminated the increase in ENaC NPo with PRL exposure. PRL also increased cAMP in A6 cells, consistent with signaling through the cAMP-dependent PKA pathway. We also identified that PRL induced activity of a 2-pS anion channel with outward rectification, electrophysiological properties consistent with ClC4 or ClC5. RT-PCR only detected ClC4, but not ClC5 transcripts. Here, we show for the first time that PRL activates sodium and chloride transport in renal epithelial cells via ENaC and ClC4.
许多激素途径参与肾上皮钠通道（ENaC）功能的调节，这是维持血容量和控制血压的关键过程。在本研究中，我们检测了肽类激素催乳素（PRL）是否调节肾上皮细胞（A6）中的ENaC功能。向基底外侧施加几种不同浓度的PRL可显著刺激A6细胞的跨上皮电流，增加氨氯地平敏感（ENaC）电流和氨氯地平不敏感电流。使用细胞贴附式膜片钳技术，我们确定PRL增加了顶端膜中ENaC的数量（N）和开放概率（Po）。用H-89抑制PKA消除了PRL对氨氯地平敏感和不敏感跨上皮电流的影响，并消除了PRL暴露后ENaC NPo的增加。PRL还增加了A6细胞中的cAMP，这与通过cAMP依赖性PKA途径的信号传导一致。我们还鉴定出PRL诱导了一种具有外向整流的2-pS阴离子通道的活性，其电生理特性与ClC4或ClC5一致。RT-PCR仅检测到ClC4转录本，未检测到ClC5转录本。在此，我们首次表明PRL通过ENaC和ClC4激活肾上皮细胞中的钠和氯转运。
