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.

除了它们在逆流交换中的作用之外，直降血管（DVR）是阻力血管，通过其向肾髓质供应血流。该项目资助的一般假设是，导致高血压的基本机制是活性氧（ROS）的产生增加。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产生增加导致一氧化氮（NO）生物利用度降低和DVR血管紧张素增强。初步数据表明，血管紧张素II（AngII）增强了DVR和肾单位中的ROS形成，并且ROS形成的阻断增加了DVR NO的形成并减弱了血管收缩。我们将探讨我们的中心假设我们的中心假设有以下具体目标。在目标1中，我们将测试的假设，ROS的形成调制NO的产生外髓DVR（OMDVR）从血管束和外髓肾单位从束间区域分离。作为NO生物利用度的指标，我们将测试AngII诱导的高血压对乙酰胆碱引起的OMDVR血管舒张的影响。我们还将使用荧光探针直接测量OMDVR和束间肾单位的ROS和NO生成。在目标2中，我们将确定在AngII诱导的高血压过程中负责ROS和NO生成的酶中的哪一种被调节。采用真实的时间PCR、外髓匀浆免疫印迹、原位杂交和免疫细胞化学等方法检测NADPH氧化酶、eNOS、nNOS和ecSOD在OMDVR和肾单位中的表达。我们还将测试NADPH氧化酶、eNOS和nNOS基因缺失在ROS和NO产生中的作用。在aim3中，我们将检验高血压伴随着氧化防御机制降低的假设。在目标3中，我们将检验高血压伴随着氧化防御机制降低的假设。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。