Renal Vascular Oxidative Stress in Hypertension

血管紧张素II(Ang II)对肾皮质(传入小动脉)和延髓(直肠外髓降血管，OMDVR)的主要阻力血管的影响被认为是高血压的关键作用。长期暴露于血管紧张素转换酶II会导致对肾血管阻力增强的升压反应减慢。这项提案将研究Ang II诱导的氧化应激是这些肾性高血压机制的基础这一概念。这项提案将研究Ang II诱导的氧化应激是这些肾性高血压机制的基础这一概念。血管紧张素转换酶II诱导的氧化应激意味着活性氧(ROS)的生成增加或代谢减少，特别是超氧阴离子(P2)、过氧化氢(H_2O_2)和羟基自由基(OH)。这一概念将在选定的基因敲除模型中进行研究，以评估通过p47/Phox NAD(P)H氧化酶产生的ROS的缺失，或通过eNOS产生的NO的缺失，以及细胞外超氧化物歧化酶(EC-SOD)或多巴胺5受体(D5-R)的缺失对氧化防御的影响。子项目1将利用新的方法在体内结合微穿刺法和微灌注法测量PO2的管内和微动脉。它将研究Ang II刺激NAD(P)H氧化酶依赖的ROS的假设。这会导致功能性一氧化氮缺乏，肾脏供氧能力下降，氧气利用效率低下。由此导致的肾脏PO2的下降抑制了正在进行的ROS的产生。子项目2将结合在子项目#3和子项目#4中开发的[NO]和[ROS]的收缩性能的测量，对比在Ang II变化期间分离的肾传入和肠系膜阻力血管的反应。它将测试Ang II选择性的肾皮质血管收缩作用是由于依赖ROS的[NO]减少，从而促进传入小动脉的血管收缩，而ROS实际上是通过内皮依赖的超极化来松弛肠系膜血管。子项目3将使用新的血管[ROS]和[NO]荧光显微镜研究，结合单个OMDVR释放NO的直接测量，研究Ang II和PO2(在子项目#1中定义)对隔离灌流OMDVR中ROS和NO的调节。子项目4将在多巴胺5受体(D5-R)基因敲除小鼠中使用新的高血压和氧化应激模型。它将研究结构性活性D5-R与Ang II在NAD(P)H氧化酶和其他细胞氧化剂或防御途径的肾脏调节中的相互作用。D5-R基因敲除的功能效应将在子项目#1、#2和#3中进行探索。这是一个综合功能基因组学方法，用于研究肾脏内Ang II刺激的ROS介导的高血压机制。

Critical hypertensive roles for angiotensin II (Ang II) have been postulate for its effects on the major resistance vessels of the renal cortex (afferent arteriole) and medulla (outer medullary descending vasa recta, OMDVR). Prolonged exposure to Ang II leads to slow pressor response to enhancement of renal vascular resistance. This proposal will examine the concept that Ang II-induced oxidative stress underlies these renal hypertensive mechanisms. This proposal will examine the concept that Ang II-induced oxidative stress underlies these renal hypertensive mechanisms. Ang II-induced oxidative stress implies either an enhanced generation, or decreased metabolism of reactive oxygen species (ROS), notably superoxide anion (P2), hydrogen peroxide (H2O2)and hydroxyl radical (OH). This concept will be studied in selected knockout models to assess the effects of deletion of ROS generated via p47/phox NAD(P)H oxidase, or NO generated via eNOS and of oxidant defense from the effects of deletions of extracellular superoxide dismutase, (EC-SOD) or dopamine 5 receptor (D5-R). Subproject 1 will utilize novel methods for intra-tubular and arteriolar measurements of pO2 combined with micropuncture and microperfusion in vivo. It will study the hypothesis that Ang II stimulates NAD(P)H oxidase-dependent ROS. This causes functional NO deficiency, a fall in renal O2 delivery and inefficient O2 utilization. The resulting fall in renal pO2 restrains ongoing ROS generation. Subproject 2 will contrast responses in isolated renal afferent and mesenteric resistance vessels during changes in Ang II combining measurements of contractility with [NO] and [ROS] developed in subprojects #3 and #4. It will test the concept that selective renal cortical vasoconstrictor actions of Ang II are due to ROS-dependent reduction in [NO], thereby promoting vasoconstriction of the afferent arteriole, whereas ROS actually relax mesenteric vessels via endothelium- dependent hyperpolarization. Subproject 3 will use novel fluorescence microscopy studies of vascular [ROS] and [NO], combined with direct measures of NO releases from single OMDVR to study the regulation of ROS and NO by Ang II and pO2 (defined in subproject #1) in isolated perfused OMDVR. Subproject 4 will use the novel model for hypertension and oxidative stress in the dopamine 5 receptor (D5-R) knockout mouse. It will investigate the interaction of the constitutively active D5-R with Ang II in the renal regulation of NAD(P)H oxidase, and other cellular oxidant or defense pathways. The functional effects of D5- R knockout will be explored in subprojects #1, #2, and #3. This is a proposal for an integrated functional genomics approach to the study of hypertensive mechanisms mediated by Ang II-stimulated ROS within the kidneys.