Renal Vascular Oxidative Stress in Hypertension

血管紧张素II （Ang II）对肾皮质（传入小动脉）和髓质（外髓降血管直血管，OMDVR）的主要抵抗血管的影响已被假设为高血压的关键作用。长期暴露于Ang II导致对肾血管阻力增强的缓慢降压反应。本研究将探讨Ang ii诱导的氧化应激是这些肾性高血压机制的基础。本研究将探讨Ang ii诱导的氧化应激是这些肾性高血压机制的基础。Ang 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，尤其是超氧阴离子（P2）、过氧化氢（H2O2）和羟基自由基（OH）。这一概念将在选定的敲除模型中进行研究，以评估p47/phox NAD(P)H氧化酶产生的ROS或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）缺失对氧化防御的影响。子项目1将采用新的方法，结合微穿刺和微灌注，在体内测量管内和动脉内的pO2。它将研究Ang II刺激NAD(P)H氧化酶依赖性ROS的假设。这导致功能性NO缺乏，肾氧输送下降和氧利用效率低下。由此导致的肾pO2下降抑制了正在进行的ROS生成。子项目2将结合子项目#3和#4中开发的[NO]和[ROS]的收缩性测量，对比在Ang II变化期间孤立肾传入和肠系膜阻力血管的反应。它将验证Ang II的选择性肾皮质血管收缩作用是由于ROS依赖性的[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性的超极化使肠系膜血管放松。子项目3将使用新型荧光显微镜研究血管[ROS]和[NO]，并结合单个OMDVR中NO释放的直接测量，研究孤立灌注的OMDVR中Ang II和pO2（在子项目#1中定义）对ROS和NO的调节。子项目4将使用多巴胺5受体（D5-R）敲除小鼠的高血压和氧化应激新模型。它将研究组成活性D5-R与Ang II在肾脏调节NAD(P)H氧化酶和其他细胞氧化或防御途径中的相互作用。D5- R基因敲除的功能效应将在子项目#1、#2和#3中探讨。这是一项整合功能基因组学方法的建议，用于研究angii刺激的肾脏内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.