Regulation of renal afferent arteriolar function by ROS

ROS对肾传入小动脉功能的调节

• 批准号: 6656538
• 负责人: CHRISTOPHER S WILCOX
• 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/6656538
• 关键词: NAD(P)H oxidoreductase; acetylcholine; angiotensin /renin /aldosterone hypertension; angiotensin II; arterioles; dopamine receptor; fluorescence microscopy; free radical oxygen; gene expression; gene targeting; genetically modified animals; kidney circulation; kidney function; laboratory mouse; nitric oxide synthase; oxidative stress; superoxide dismutase; vascular resistance; vasomotion

Ang II action within the kidneys is implicated in may models of human hypertension. When infused at initially subpressor doses, Ang II causes a slow pressor response with potent constriction of the renal afferent arteriole that increases over time. We will examine the concept that the reactivity of the renal afferent arteriole to Ang II is dependent on the generation of reactive oxygen species (ROS) derived from p47/phox- dependent NAD(P)H oxidase. These effects of oxidative stress are countered by oxidant defense mechanisms mediated via extracellular superoxide dismutase (EC-SOD) and intracellularly via a signaling cascade that is regulated by the constitutively-active dopamine 5 receptor (D5-R), We will test whether the functional effect of oxidative stress in the renal afferent arteriole is to enhance tone by reducing eNOS-derived NO. In contrast, the tone of the mesenteric resistance vessels may be blunted by an endothelium-dependent hyperpolarizing factor (EDHF) whose response may actually be mediated by an ROS. These differential effects of oxidative stress could provide for selective effects of Ang II mediated via ROS, on renal afferent arterioles. Studies will contrast isolated afferent and mesenteric resistance vessels from mice. Measurement of contraction or relaxation will be related to measurements of vascular [NO] and [ROS] assess by fluorescence microscopy and to measurements of the mRNA and protein expression of key mediators in these vessels. The first aim will utilize p47/phox NAD(P)H oxidase and eNOS Knockout mice to define the roles of these systems in the acute microvascular responses to Ang II. The second aim will assess the expression of key oxidases and antioxidant and pathways in microvessels during prolonged Ang II infusion. The third aim will examine the functional consequences of finding sin Aim 2. It will contrast acetylcholine-induced relaxation in afferent and mesenteric arterioles, and study the effect of O2-dependent changes in ROS generation. Arterioles will be dissected from mice during prolonged infusion of Ang II or vehicle to related relaxation to vascular [NO] and [ROS] in models deleted in eNOS, p47/phox, EC-SOD and D5-R. These protocols are part of an integrated approach to studying the roles of ROS in the renal mechanism of Ang II-induced hypertension.

Ang II在肾脏内的作用与许多人类高血压模型有关。当以最初的亚压剂量输注时，Ang II引起缓慢的升压反应，随着时间的推移，肾传入小动脉的强烈收缩会增加。我们将研究肾传入小动脉对Ang II的反应性取决于p47/phox依赖性NAD(P)H氧化酶产生的活性氧（ROS）的概念。氧化应激的这些作用可通过细胞外超氧化物歧化酶（EC-SOD）和细胞内由组成活性多巴胺5受体（D5-R）调节的信号级联介导的氧化防御机制来抵消。我们将测试氧化应激在肾传入小动脉中的功能作用是否通过减少enos衍生的NO来增强张力。相反，肠系膜抵抗血管的张力可能被内皮依赖性超极化因子（EDHF）钝化，其反应实际上可能是由ROS介导的。氧化应激的这些差异效应可能提供了通过ROS介导的Ang II对肾传入小动脉的选择性作用。研究将对小鼠分离的传入血管和肠系膜抵抗血管进行对比。收缩或舒张的测量将与荧光显微镜下血管[NO]和[ROS]的测量以及这些血管中关键介质的mRNA和蛋白质表达的测量有关。第一个目标是利用p47/phox NAD(P)H氧化酶和eNOS敲除小鼠来确定这些系统在急性微血管反应中对Ang II的作用。第二个目的是评估长时间输注Ang II时微血管中关键氧化酶和抗氧化途径的表达。第三个目标将检查在目标2中找到sin的功能后果。对比乙酰胆碱诱导的传入和肠系膜小动脉松弛，研究o2依赖性变化对ROS生成的影响。在eNOS、p47/phox、EC-SOD和D5-R缺失的模型中，在长时间输注Ang II或载药期间剥离小鼠小动脉，使血管[NO]和[ROS]相关松弛。这些方案是研究ROS在Ang ii诱导的高血压肾机制中的作用的综合方法的一部分。