SODIUM INTAKE AND ANGIOTENSIN II IN MICROCIRCULATORY RAREFACTION

项目5检查血管紧张素II在解剖学损失中的作用 在高盐饮食的动物中发生的微血管（稀疏）。 他已经证明，钠摄入量的增加会引发一系列的 事件最终在整个过程中大量稀疏 正常大鼠微循环。在上一个融资期， 表明微循环的稀薄会导致 总外周阻力增加，组织灌注减少， 氧气输送减少和器官功能受损虽然 这种情况发生的机制还没有很好地理解，一些关键 观察结果指出，肾素-血管紧张素系统在这一过程中的作用。 效果首先，在HS期间将ANGII维持在正常水平 饮食完全消除稀疏。二、盐摄入量升高 导致微血管AT/1受体减少， 刺激和微血管AT/2受体的增加， 生长抑制第三，ANGII系统性输注， 升压水平，或局部进入骨骼肌肌层， 诱导显著微血管生长。本研究将审查 假设在高缝翼进气量期间， 局部或循环ANGII介导稀疏。我们进一步假设 其作用并增强由ANGII抑制引起的稀疏。 使用高灵敏度和特异性的方法测量组织 ANGII是在我们的实验室开发的，我们已经表明， 提睾肌微血管中ANGII的浓度至少为 5倍于血浆中的测量值。据我们所知，这是一些最 直接证据支持局部肾素-血管紧张素系统的作用 在微循环中。本项目的目标是探索 局部血管肾素-血管紧张素系统的调节 微循环，并确定其在微血管稀疏中的作用。 ANGII在微循环重塑中的作用将是 使用直接静脉内和 局部输注ANGII，以精确控制循环和局部 浓度的肾素基因的局部调控机制 表达将在一组独特的同类Dahl大鼠品系中进行研究， 其中R型肾素基因已经渗入S型大鼠的基因中， 背景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， 假设调节肾素-血管紧张素系统是负责 因为盐的作用而变得稀薄。几个令人兴奋的应用和 新的技术将能够检验这一假设。微血管 将使用计算机视频显微镜在体内评价功能。 由盐引发的微循环形态学变化将 使用定量体视学技术进行评估， 开发和广泛使用。血管紧张素受体的定位 微循环将使用高度特异性的AT/1进行， AT/2抗体用于免疫组织化学和蛋白免疫印迹 分离自骨骼肌解剖的微血管。的影响 盐摄入量和ANGII循环水平对AT/1分布的影响， AT/2 mRNA和蛋白在微循环中的表达将被抑制， 使用竞争性RT-PCR、免疫组织化学和Western印迹法测定 印迹以确定这些受体的表达是否受 ANGII。最后，通过测量循环和血管ANGII水平， HPLC联合局部输注ANGII和ANGI及局部阻断 ACE将确定局部作用血管紧张素系统的变化 在微循环的重塑中起着重要作用。

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.