SODIUM INTAKE AND ANGIOTENSIN II IN MICROCIRCULATORY RAREFACTION

微循环稀薄中的钠摄入量和血管紧张素 II

• 批准号: 6588507
• 负责人: ANDREW S. GREENE
• 金额: $ 28.24万
• 依托单位: MEDICAL COLLEGE OF WISCONSIN
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6588507
• 关键词: angiogenesis; angiotensin II; dietary sodium; genetic strain; growth inhibitors; high performance liquid chromatography; histopathology; hormone receptor; immunocytochemistry; laboratory rat; microcirculation; neuropeptide receptor; nutrition related tag; polymerase chain reaction; protein localization; receptor expression; renin angiotensin system; salt intake; vascular resistance; video microscopy; western blottings

Project 5 examines the role of the angiotensin II in the anatomical loss of microvessels (rarefaction) that occurs in animals fed a high salt diet. He have shown that an elevation in sodium intake can trigger a series of events culminating in a substantial rarefaction throughout the microcirculation in normal rats. In the previous funding period we have demonstrated that rarefaction of the microcirculation can cause an increase in total peripheral resistance, reduced tissue perfusion, decreased oxygen delivery, and impaired organ function. Although the mechanism by which this occurs are not well understood, a number of key observations point to a role for the renin-angiotensin system in this effect. First, maintenance of ANGII at normal levels during periods of HS diet completely eliminates rarefaction. Second, elevated salt intake causes a decrease in microvascular AT/1 receptors which are growth stimulatory and an increase in the microvascular AT/2 receptors which are growth inhibitory. Third, ANGII infused either systematically at sub- pressor levels, or locally into the skeletal muscle interstitium, can induce significant micro-vessel growth. The present study will examine the hypothesis that during period of high slat intake, suppression of either local or circulating ANGII mediate rarefaction. We further hypothesize that actions and augment the rarefaction caused by ANGII suppression. Using a highly sensitive and specific method for the measurement of tissue ANGII that was developed in our laboratories, we have shown that the concentration of ANGII in microvessels of the cremaster muscle is at least 5 times that measured in plasma. To our knowledge this is some of the most direct evidence supporting a role for the local renin-angiotensin system in the microcirculation. The goal of this project is to explore the regulation of the local vascular renin-angiotensin system in the microcirculation and to determine its role in microvascular rarefaction. The role of ANGII in the remodeling of the microcirculation will be assessed in chronically instrumented rats using direct intravenous and local infusions of ANGII to precisely control circulating and local concentrations. Mechanisms of the local control of the renin gene expression will be studied in a unique set of congenic Dahl rat strains in which the R renin gene has been introgressed into the S rat genetic background. We will take advantage of the difference in the renin response in these two unique, genetically matched, strains of rats to test the hypothesis that modulation of the renin-angiotensin system is responsible for the rarefaction due to salt. The application of several exciting and novel techniques will enable examination of this hypothesis. Micro-vessel function will be evaluated in vivo using computer video microscopy. Morphological changes in the microcirculation triggered by salt will be evaluated using quantitative stereological techniques that we have developed and used extensively. Localization of angiotensin receptors in the microcirculation will be carried out using highly specific AT/1 and AT/2 antibodies for immune-histochemistry and immuno-blotting of protein isolated from microvessels dissected from skeletal muscle. The effects of salt intake and circulating levels of ANGII on the distribution of AT/1, and AT/2 mRNA and protein throughout the microcirculation will be determined using competitive RT-PCR, immuno-histochemistry and Western blots to determine if the expression of these receptors is regulated by ANGII. Finally, measurements of circulating and vascular ANGII levels by HPLC combined with local infusion of ANGII and ANGI and local blockade of ACE will determine if change in the locally acting angiotensin system plays a significant role in the remodeling of the microcirculation.

项目5检查血管紧张素II在解剖学损失中的作用。 在喂食高盐食物的动物中出现的微血管(稀疏)。 他已经证明，钠摄入量的增加可以引发一系列 事件最终在整个世界范围内出现了相当稀少的情况 正常大鼠的微循环。在上一个资助期，我们有 证明了微循环的稀疏会导致 总外周阻力增加，组织灌注量减少， 氧气输送减少，器官功能受损。尽管 发生这种情况的机制还不是很清楚，有许多关键 观察表明，肾素-血管紧张素系统在这一过程中发挥了作用。 效果。第一，在合并症期间，将血管紧张素转换指数维持在正常水平 饮食完全消除了稀缺性。第二，食盐摄入量增加 导致生长中的微血管AT/1受体减少 刺激和增加微血管AT/2受体，这是 生长抑制。第三，Angii要么系统地在亚洲区 加压水平，或局部进入骨骼肌间质，可以 诱导显著的微血管生长。本研究将审查 假设在板岩摄入量高的时期，抑制 局部或循环中的血管疏松起调节作用。我们进一步假设 这一行动并扩大了安吉镇压造成的稀少。 使用一种高度灵敏和特殊的方法测量组织 Angii是我们实验室开发的，我们已经证明了 提睾肌微血管中的血管紧张素Ⅱ浓度至少为 是在血浆中测得的5倍。据我们所知，这是世界上 支持局部肾素-血管紧张素系统作用的直接证据 在微循环中。这个项目的目标是探索 局部血管肾素-血管紧张素系统的调节 并确定其在微血管疏松中的作用。 血管紧张素转换酶在微循环重塑中的作用 在慢性仪器化大鼠中使用直接静脉注射和 局部输注血管紧张素以精确控制循环和局部 浓度。肾素基因的局部调控机制 将研究在一组独特的同源Dahl大鼠品系中的表达 其中R肾素基因已导入S大鼠的遗传 背景资料。我们将利用肾素反应的差异 在这两个独特的、基因匹配的老鼠品系中测试 肾素-血管紧张素系统调节机制的假说 因为盐的缘故而变得稀薄。几种激动人心的方法的应用 新的技术将使对这一假设的检验成为可能。微血管 将使用计算机视频显微镜在活体内评估功能。 盐引发的微循环的形态变化将是 使用我们拥有的定量体视学技术进行评估 被广泛开发和使用。血管紧张素受体在心脏的定位 微循环将使用高度特异的AT/1和 AT/2抗体用于蛋白质的免疫组织化学和免疫印迹 从骨骼肌解剖的微血管中分离出来。的影响 盐摄入量和循环水平对AT/1分布的影响 而AT/2的mRNA和蛋白将贯穿微循环 采用竞争性RT-PCR、免疫组织化学和Western 印迹杂交以确定这些受体的表达是否受 安吉。最后，通过测量循环和血管中的血管紧张素Ⅱ水平 高效液相色谱法联合局部输注血管紧张素和血管紧张素转换酶及局部封闭 ACE将确定局部作用的血管紧张素系统是否发生变化 在微循环重塑中起着重要作用。