Salt Absorption by the THAL: Role of NKCC2 trafficking

细胞膜上的钠转运体的数量受动态插入、提取和， 运输车的回收利用。这些过程统称为贩运。在某些形式的人类和 实验性高血压食盐滞留是由心尖部钠离子转运体异常高水平引起的 部分肾单位节段的细胞膜。粗大的升肢(THAL)吸收NACI并有助于 盐和水的平衡，从而影响血压。Thal对NaCI的吸收主要是 受NKCC2调节，NKCC2是一种顶端的Na/K/2CI共转运体，介导Na和Cl进入细胞。到目前为止，它 目前尚不清楚NKCC2的贩运是否规范了NACI的吸收。目前也不清楚血管活性是否 刺激和抑制THAL吸收NACI的激素调节NKCC2水平 通过影响顶膜的运输而影响顶膜。我们假设Thal对NaCI的吸收是 在cAMP和cAMP刺激的过程中，NKCC2部分地通过运输到顶膜来调节 被一氧化氮抑制。NKCC2在根尖膜中的增强插入有助于盐滞留 在盐敏感型高血压模型中。在Aim I中，我们将检查NKCC2在根尖是否有水平 膜和NaCI的吸收由NKCC2的插入和恢复来调节。在AIM II中，我们将研究 刺激依赖NKCC2的NACI通过cAMP进入Thals的激素是否增加了NKCC2 在根尖膜中的水平。在目标III中，我们将研究一氧化氮是否抑制NKCC2依赖的NACI 通过降低根尖膜中NKCC2的水平进入。最后，我们将检查是否基本和 盐敏感型TALL顶膜激素刺激的NKCC2水平升高 动物。我们将使用最先进的技术来测量NKCC2在隔离大鼠中的贩运和活动 萨尔。 来自这项提案的数据将增加我们对THAL如何调节盐分吸收的理解 目前，利尿剂已在正常和对盐敏感的动物中得到应用，并将为利尿剂的开发确定新的靶点。

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.