Regulation of renal afferent arteriolar function by ROS

Ang II在肾脏内的作用与人类高血压的五月模型有关。当以最初的降压剂量输注时，Ang II引起缓慢的升压反应，并伴随着肾传入小动脉的强烈收缩，并随着时间的推移而增加。我们将检验肾传入小动脉对Ang II的反应性依赖于P47/Phox依赖的NAD(P)H氧化酶产生的活性氧物种(ROS)的概念。氧化应激的这些影响可以通过细胞外超氧化物歧化酶(EC-SOD)介导的氧化防御机制和细胞内由固有活性的多巴胺5受体(D5-R)调节的信号级联来对抗，我们将测试氧化应激在肾传入小动脉的功能效应是否通过减少eNOS衍生的NO来增强张力。相反，肠系膜阻力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。这些不同的氧化应激效应可能为血管紧张素Ⅱ通过ROS介导的对肾传入小动脉的选择性作用提供了条件。研究将对比分离的小鼠传入血管和肠系膜阻力血管。收缩或松弛的测量将与通过荧光显微镜评估的血管[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基因敲除小鼠来确定这些系统在Ang II急性微血管反应中的作用。第二个目标是评估在长时间Ang II输注过程中微血管中关键氧化酶和抗氧化剂的表达及其途径。第三个目的将研究发现SIN的功能后果2。它将对比乙酰胆碱诱导的传入小动脉和肠系膜小动脉的松弛，并研究氧依赖的变化在ROS产生中的作用。在eNOS、P47/Phox、EC-SOD和D5-R缺失的模型中，在长时间注射Ang II或载体以松弛血管[NO]和[ROS]的过程中，将从小鼠身上解剖小动脉。这些方案是研究ROS在Ang II诱导高血压的肾脏机制中作用的综合方法的一部分。

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.