Role of Aldosterone in Cardiac Remodeling

描述（由申请人提供）：醛固酮与心肌重塑和衰竭过程有关。醛固酮可能通过多种机制调节炎症、心肌细胞收缩和舒张、氧化应激和间质基质而影响心肌表型。在体外研究中，醛固酮诱导肌细胞凋亡、p67 phox和促炎信号介质如NOS 2。这些观察使我们假设，醛固酮介导的心肌细胞的表型反应，血流动力学过载和增加醛固酮系统刺激。过氧化物酶体增殖物激活受体（过氧化物酶体增殖物激活受体）信号转导，虽然调节能量控制，减轻心肌肥大，氧化应激和凋亡，并可能通过途径，如炎症改善心肌重塑。我们将通过操纵小鼠体内和体外心肌细胞和成纤维细胞中的醛固酮水平及其与PPARs在分子、细胞和器官水平上介导结构和功能重塑的相互作用来探索这些途径。在目的1中，我们将测试醛固酮和PPARs在介导压力超负荷心脏重塑中的作用。我们将检验PPARs抑制醛固酮诱导的不良心脏重塑的假设。我们将使用压力超负荷和慢性醛固酮输注的小鼠。我们将使用合成的PPAR激活剂非诺贝特和曲格列酮来确定心脏重构是否被抑制，并进一步测试醛固酮是否通过PPAR α缺失小鼠心肌中慢性炎症或氧化应激的进展介导重构。在目的2中，我们将测试醛固酮在心肌重塑中诱导肥大/增殖和凋亡表型的作用。在体内实验中，我们将测试醛固酮通过a）EGFR和MAPK途径和B）氧化应激诱导心肌表型的机制。在目标3中，我们将测试醛固酮在介导异常心肌细胞收缩表型中的作用。我们将检验醛固酮对心肌细胞收缩表型有急性和慢性作用的假设。在体外短期（min）或长期（hr）暴露于外源性醛固酮后，将在成年大鼠和小鼠肌细胞中同时测量肌细胞收缩/舒张和细胞内钙瞬变。这些研究将为压力超负荷心脏中醛固酮信号传导机制提供新的理解，并将与患者心力衰竭的常见原因直接相关。

DESCRIPTION (provided by applicant): Aldosterone is implicated in the process of myocardial remodeling and failure . Aldosterone may affect myocardial phenotype by regulating inflammation, myocyte contraction and relaxation, oxidative stress, and the interstitial matrix through a variety of mechanisms. In in vitro studies, aldosterone induces myocyte apoptosis, p67 phox and pro-inflammatory signal mediators such as NOS2. These observations lead us to the hypothesis that aldosterone mediates the phenotypic responses of myocardial cells in hemodynamic overload and increased aldosterone system stimulation . Peroxisome proliferator-activated receptor (PPAR) signaling , although regulators of energy control, attenuate cardiac hypertrophy, oxidative stress and apoptosis and may improve myocardial remodeling through pathways such as inflammation . We will explore these pathways by manipulating aldosterone levels, in vivo in mice and in vitro in cardiac myocytes and fibroblasts and their interaction with PPARs in mediating structural and functional remodeling at the molecular, cellular and organ levels. In Aim 1 we will test the role of aldosterone and PPARs in mediating pressure overload cardiac remodeling . We will test the hypothesis that PPARs inhibit aldosterone-induced adverse cardiac remodeling. We will use mice with pressure overload and chroni c aldosterone infusions . We will use synthetic PPAR activators, fenofibrate and troglitazone, to determine if cardiac remodeling is inhibite d and further test if aldosterone mediates remodeling via progression of chronic inflammation or oxidative stress in the myocardium of PPARalpha null mice. In Aim 2 we will test the role of aldosterone in inducing a hypertrophic/proliferative and apoptotic phenotype in myocardial remodeling . In in vivo experiments, we will test the mechanism whereby aldosterone induces a myocardial phenotype via a) the EGFR and MAPK pathway; and b) oxidative stress. In Aim 3 we will test the role of aldosterone in mediating an abnormal myocyte contractile phenotype. We will test the hypothesis that aldosterone exerts both acute and chronic effects on myocyte contractile phenotype. Myocyte contraction/relaxation and intracellular calcium transients will be measured simultaneously in adult rat and mouse myocytes following short (min ) or long (hrs) term exposure to exogenous aldosterone in vitro. These studies will provide new understanding of the mechanisms of aldosterone signaling in the pressure overload heart and will have direct relevance to a common cause of heart failure in patients.