Salt-sensitive hypertension: Role of renal superoxide

描述（由申请人提供）：促进肾盐和水潴留的因素与有利于排泄的因素之间存在平衡。盐潴留不当可能导致高血压。这个项目的重点是超氧化物（O2-），它有利于盐和水的保留。肾O2-是肾脏功能的重要调节因子，与盐敏感性高血压有关。Henle肾袢的厚升肢是导致盐敏感性高血压患者钠离子潴留不适当的肾元节段之一，也是肾袢利尿剂的作用部位。在上一个资助期，我们发现O2-通过增强腔内Na/K/2CI共转运蛋白的活性来增加厚升肢转运。这种作用是由于蛋白激酶C （PKC）的激活和一氧化氮（NO）的清除。然而，很少有研究直接探讨O2的产生是如何沿着肾元调控的。尿流通过粗大的上升肢不是静止的，但由于乳头的蠕动，尿流从超过25 nl/min到低至0 nl/min（实际上停止）急剧变化。我们的初步数据表明，通过厚升肢增加的管腔血流（THAL-flow）刺激了O2的产生。我们的一般假设是，增加尿流量的因素，从而增加了厚升肢的拉伸、压力或剪切应力，从而增加了氧的产生，从而促进了NaCI的吸收，从而促进了Na的保留。厚升肢O2-增强引起的Na潴留增加可能在高血压和其他与Na潴留相关疾病的发病机制中起重要作用。Aim 1将测试急性增加thal流量是否会引起NADPH氧化酶的组装和激活，从而增强O2的生成和NaCI的吸收。目的2和3将研究血流刺激O2产生的信号级联反应，重点是蛋白激酶C和小g蛋白Rac1。目的4将研究流动诱导的NO如何调节NADPH氧化酶活性及其对NaCI吸收的影响。我们将采用最先进的技术来实现这些目标，包括荧光能量转移和体内病毒转导，以及标准的生理、生化和药理学技术。该项目的成功完成将使我们对肾脏中O2-的生成及其在盐潴留中的作用有新的认识，并预测高血压治疗的新靶点。

DESCRIPTION (provided by applicant): There is a balance between factors promoting renal salt and water retention and those favoring excretion. Inappropriate salt retention may lead to hypertension. This project focuses on superoxide (O2-), which favors salt and water retention. Renal O2- is an important regulator of kidney function and has been implicated in salt-sensitive hypertension. The thick ascending limb of the loop of Henle is one of the nephron segments responsible for inappropriate NaCI retention in salt-sensitive hypertension and is the site of action of loop diuretics. In the last funding period we showed that O2- increased thick ascending limb transport by enhancing the activity of the luminal Na/K/2CI cotransporter. This effect was due to both activation of protein kinase C (PKC) and scavenging of nitric oxide (NO). However, few studies have directly addressed how O2- production is regulated along the nephron. Urine flow through thick ascending limbs is not static, but acutely varies from more than 25 nl/min to as little as 0 nl/min (actually stopping) due to peristalsis of the papilla. Our preliminary data show that increasing luminal flow through the thick ascending limb (THAL-flow) stimulates O2- generation. Our general hypothesis is that factors that increase urine flow and therefore augment stretch, pressure or shear stress in the thick ascending limb enhance O2- production, which in turn promotes NaCI absorption and therefore Na retention. The increase in Na retention caused by enhanced O2- in the thick ascending limb may be important in the pathogenesis of hypertension and other diseases associated with Na retention. Aim 1 will test whether acutely increasing THAL-flow causes the assembly and activation of NADPH oxidase, thereby enhancing O2- generation and NaCI absorption. Aims 2 and 3 will study the signaling cascades responsible for flow-stimulated O2- production focusing on protein kinase C and the small G-protein Rac1. Aim 4 will investigate how flow-induced NO regulates NADPH oxidase activity and its impact on NaCI absorption. We will employ state of the art techniques to address these aims, including fluorescence energy transfer and in vivo viral transduction in addition to standard physiological, biochemical and pharmacological techniques. Successful completion of this project will give us new insights into how O2- is generated in the kidney as well as its role in salt retention, and predict new targets for treatment of hypertension.