Oxidative stress in the renal medulla

肾髓质的氧化应激

• 批准号: 6656539
• 负责人: THOMAS L PALLONE
• 金额: $ 33.6万
• 依托单位: GEORGETOWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6656539
• 关键词: NAD(P)H dehydrogenase; angiotensin /renin /aldosterone hypertension; angiotensin II; dopamine receptor; fluorescent dye /probe; isozymes; kidney circulation; laboratory mouse; nitric oxide; nitric oxide synthase; oxidative stress; renal medulla; superoxide dismutase; vasomotion

In addition to their role in countercurrent exchange, descending vasa recta (DVR) are resistance vessels through which blood flow to the renal medulla is supplied. The general hypothesis of this program project grant is that a fundamental mechanism that leads to hypertension is enhanced production of reactive oxygen species (ROS). The general hypothesis to be tested in this subproject is that, during hypertension, increased ROS production in the medulla leads to reduction of nitric oxide (NO) bioavailability and enhanced vasomotor tone of DVR. Preliminary data shows that angiotensin II (AngII) enhances ROS formation in DVR and nephrons and that blockade of ROS formation increase DVR NO formation and blunts vasoconstriction. We will explore our central hypothesis our central hypothesis with the following specific aims. In aim 1 we will test the hypothesis that ROS formation modulates NO generation in outer medullary DVR (OMDVR) isolated from the vascular bundles and outer medullary nephrons isolated from the interbundle region. As an index of NO bioavailability, we will test the effect of AngII induced hypertension on OMDVR vasodilation by acetylcholine. We will also directly measure ROS and NO generation ROS and NO generation by OMDVR and interbundle nephrons using fluorescent probes. In aim 2 we will determine which of the enzymes responsible for ROS and NO generation is modulated during AngII induced hypertension. We will measure NADPH oxidase, eNOS, nNOS and ecSOD expression in OMDVR and nephrons by real time PCR, western blot of outer medullary homogenates, in situ hybridization and immunocytochemistry. We will also test the effect of NADPH oxidase, eNOS and nNOS gene deletion in ROS and NO generation. In aim3, we will test the hypothesis that hypertension is accompanied by a decreased in oxidant defense mechanisms. In aim 3, we will test the hypothesis that hypertension is accompanied by a decreased in oxidant defense mechanisms. We will examine the effects of gene deletion of extracellular superoxide dismutase and the dopamine D5 receptor on ROS generation and NO bioavailability. We will also determine the extent to which the D5 receptor acts through hemeoxygenase.

除了在逆流交换中的作用外，直降血管(DVR)也是阻力血管，血液通过这些血管向肾髓质供应。这项计划项目拨款的一般假设是，导致高血压的一个基本机制是增加活性氧物种(ROS)的产生。在这个子项目中要检验的一般假设是，在高血压期间，髓质中ROS产生的增加导致一氧化氮(NO)生物利用度的降低和DVR血管舒缩张力的增强。初步数据显示，血管紧张素II(AngII)促进DVR和肾单位ROS的形成，阻断ROS形成增加DVR NO的形成，钝化血管收缩。我们将探索我们的中心假说，我们的中心假说具有以下具体目标。在目标1中，我们将验证一种假设，即ROS的形成调控从维管束分离的延髓外DVR(OMDVR)和从束间区分离的延髓外肾单位(OMDVR)中NO的产生。作为NO生物利用度的指标，我们将测试血管紧张素Ⅱ诱导的高血压对乙酰胆碱扩张OMDVR的影响。我们还将使用荧光探针直接测量OMDVR和束间肾素产生的ROS和NO生成的ROS和NO。在目标2中，我们将确定在血管紧张素转换酶诱导的高血压过程中，哪些酶负责调节ROS和NO的生成。采用实时荧光定量聚合酶链式反应、外髓匀浆免疫印迹、原位杂交和免疫细胞化学等方法检测OMDVR和肾单位NADPH氧化酶、eNOS、nNOS和EcSOD的表达。我们还将检测NADPH氧化酶、eNOS和nNOS基因缺失在ROS和NO生成中的作用。在目标3中，我们将检验这一假设，即高血压伴随着氧化防御机制的降低。在目标3中，我们将检验这一假设，即高血压伴随氧化防御机制的降低。我们将研究细胞外超氧化物歧化酶和多巴胺D5受体基因缺失对ROS生成和NO生物利用度的影响。我们还将确定D5受体通过血红素加氧酶发挥作用的程度。