The Renin-Ang II System in Cardiovascular Remodeling

描述（由申请人提供）：我们研究的主要目标是确定Ang II在自发性高血压大鼠（SHR）心脏纤维化发生和进展中的分子机制。另一个目标是确定早期短期应用血管紧张素转换酶抑制剂（ACEI）预防纤维化发生和进展的机制。我们之前发现，SHR的早期、短期CAP治疗可以预防心脏纤维化，这可能是通过抑制SHR血压升高之前促纤维化环境的启动来实现的。本研究有3个具体目的：(1)确定早期、短期用CAP治疗SHR是否能通过长期阻断心脏RAS来阻止左室重构，以及这种作用是否独立于血压效应。心功能将通过超声心动图、体外灌注和血流动力学研究来监测。胶原蛋白含量、分布、表型和交联将通过生化、形态计量、分子、生物学和Western blot分析相结合来确定。Ang II和tgf - β及其受体将通过生化和分子生物学方法进行监测。(2)为了确定Ang II诱导SHR心脏纤维化的细胞和分子机制，以及它们如何被早期、短期CAP抑制。胶原异构体和调节胶原合成的蛋白质（Ang II受体、tgf - β）和调节胶原降解的蛋白质（TIMPs、pal - 1）的表达将通过RNase保护实验、Northern和Western blot分析来确定。(3)确定高血压患者心脏成纤维细胞中RAS介导心脏纤维化发生的细胞信号转导级联。信号中间体将通过Western blot分析确定。本研究将利用SHR（一种具有良好特征的遗传性高血压模型），首次研究心脏成纤维细胞体内和体外胶原合成和降解的Ang ii依赖机制，它们如何随时间变化，以及它们如何与SHR中的心功能相关。这些研究将使我们能够确定新的药物干预目标，以预防高血压患者不良心血管重构。

DESCRIPTION (provided by applicant): The major goal of our studies is to identify the molecular mechanisms underlying the role of Ang II in the development and progression of cardiac fibrosis in the spontaneously hypertensive rat (SHR). An additional goal is to determine the mechanisms underlying the ability of early, short-term application of angiotensin-converting enzyme inhibitors (ACEI) to prevent the development and progression of fibrosis. We have previously found that early, short-term CAP treatment of SHR prevents cardiac fibrosis and may do this by inhibiting the initiation of a pro-fibrotic environment prior to an increase in BP in SHR. This proposal has 3 specific aims: (1) To determine whether early, short-term treatment of SHR with CAP prevents LV remodeling through prolonged blockade of cardiac RAS and whether or not this effect is independent of blood pressure effects. Cardiac function will be monitored by echocardiography, ex vivo perfusion, and hemodynamic studies. Collagen content, distribution, phenotype, and cross-linking will be determined by a combination of biochemical, morphometric, molecular, biological, and Western blot analyses. Ang II and TGF-beta and its receptors will be monitored by biochemical and molecular biological methods. (2) To determine the cellular and molecular mechanisms underlying Ang II-induced cardiac fibrosis in SHR and how they are inhibited by early, short-term CAP. Expression of collagen isoforms and proteins that regulate collagen synthesis (Ang II receptors, TGF-beta) and proteins that regulate collagen degradation (TIMPs, PAl-l) will be determined by RNase protection assays, and Northern and Western blot analyses. (3) To identify the cellular signal transduction cascades in cardiac fibroblasts that mediate the development of cardiac fibrosis by RAS in hypertension. Signaling intermediates will be determined by Western blot analyses. This proposal will utilize SHR, a well-characterized model of genetic hypertension, and it is the first to study Ang II-dependent mechanisms of collagen synthesis and degradation in vivo and in vitro in cardiac fibroblasts, how they change over time, and how they correlate to cardiac function in SHR. These studies will allow us to identify new targets for pharmacological intervention to prevent adverse cardiovascular remodeling in hypertension.