Salt Absorption by the THAL: Role of NKCC2 trafficking

细胞膜中Na-转运蛋白的数量受动态插入、回收和 回收运输工具。这些过程统称为贩运。在某些形式的人类和 实验性高血压盐潴留是由心尖部异常高水平的钠转运蛋白引起的 一些肾单位节段的膜。厚的上升支（塔尔）吸收NaCl并有助于 盐和水的体内平衡，从而影响血压。NaCl被塔尔吸收主要是 受NKCC 2调节，NKCC 2是一种顶端Na/K/2Cl共转运蛋白，介导Na和Cl进入细胞。迄今为止， 尚不清楚NKCC 2的运输是否调节NaCl吸收。也不清楚血管活性物质是否 刺激和抑制NaCl被塔尔吸收的激素调节NKCC 2水平， 通过影响其运输来破坏顶膜。我们假设塔尔对NaCl的吸收 在cAMP刺激的过程中，部分受NKCC 2转运到顶膜的调节， 被一氧化氮抑制NKCC 2插入顶膜的增强有助于盐的保留 在盐敏感性高血压模型中。在目的I中，我们将检查心尖部中的NKCC 2水平是否 膜和氯化钠吸收通过NKCC 2的插入和回收来调节。在目标II中，我们将研究 刺激NKCC 2依赖性NaCl通过cAMP进入THAL的激素是否增加NKCC 2 在顶膜的水平。在目标III中，我们将研究一氧化氮是否抑制NKCC 2依赖性NaCl 通过降低顶膜中的NKCC 2水平进入。最后，我们将研究基础和 在盐敏感性THL中，顶膜中的NKCC 2水平增加。 动物我们将使用最先进的技术来测量NKCC 2在隔离大鼠中的运输和活性。 THAL。 该提案的数据将增加我们对塔尔如何调节盐吸收的理解， 正常和盐敏感的动物，并将确定利尿剂的发展新的目标。

The number of Na-transporters in the cell membrane is regulated by dynamic insertion, retrieval and, recycling of transporters. Collectively these processes are known as trafficking. In some forms of human and experimental hypertension salt retention is caused by abnormally high levels of Na-transporters in the apical membrane of some nephron segments. The thick ascending limb (THAL) absorbs NaCI and contributes to salt and water homeostasis, thereby influencing blood pressure. NaCI absorption by the THAL is primarily regulated by NKCC2, an apical Na/K/2CI cotransporter that mediates Na and Cl entry into the cell. To date, it is not clear whether trafficking of NKCC2 regulates NaCI absorption. It is also not clear whether vasoactive hormones that stimulate and autacoids that inhibit NaCI absorption by the THAL regulate NKCC2 levels in the apical membrane by affecting its trafficking. We hypothesize that NaCI absorption by the THAL is regulated in part by trafficking of NKCC2 into the apical membrane, in a process stimulated by cAMP and inhibited by nitric oxide. Enhanced insertion of NKCC2 into the apical membrane contributes to salt retention in models of salt-sensitive hypertension. In Aim I we will examine whether NKCC2 levels in the apical membrane and NaCI absorption are regulated by insertion and retrieval of NKCC2. In Aim II we will study whether hormones that stimulate NKCC2-dependent NaCI entry into THALs via cAMP increase NKCC2 levels in the apical membrane. In Aim III we will study whether nitric oxide inhibits NKCC2-dependent NaCI entry by decreasing NKCC2 levels in the apical membrane. Finally we will examine whether basal and hormone-stimulated NKCC2 levels in the apical membrane are enhanced in THALs from salt-sensitive animals. We will use state-of-the-art techniques to measure NKCC2 trafficking and activity in isolated rat THALs. Data from this proposal will increase our understanding of how salt absorption by the THAL is regulated in normal and salt-sensitive animals, and will identify new targets for the development of diuretics.