Prevention of heart failure and remodeling through calcium channel modulation

 描述（由申请人提供）：心肌梗死（MI）后即刻的心输出量损失触发长期心脏重塑。MI重构包括收缩力丧失和心室扩张，导致心力衰竭（HF）。心肌梗死后维持较高收缩功能的策略可能会避免最终导致HF的刺激。一个潜在的治疗靶点是Rad，一种小的GTdR，作为L型钙通道的调节剂; Rad损失促进更大的内向电流，更高的抽搐钙水平，更大的心室肌细胞缩短分数，以及增加心脏收缩力。据推测，钙稳态和收缩的这种改善可以减轻MI后收缩性的丧失。为了检验这一假设，将对Rad敲除小鼠进行冠状动脉结扎和连续超声心动图以监测心脏尺寸和功能。将使用组织学评估瘢痕大小，并且将在刺激的分离的心室肌细胞中测量胞质钙以确定Rad无效小鼠是否受到保护免于MI诱导的钙失调，从而防止瞬时幅度的损失和SR中再摄取的减慢。Rad基因敲除小鼠受到保护免于急性MI的假设-诱导的坏死和凋亡将使用经受缺血的分离的灌注心脏进行测试，随后将其染色并分析梗塞发展。还将使用晚期钆增强MRI在体内研究这些结果。据推测，Rad GT3基因的缺失将通过心肌梗死后心输出量的保护和通过启动心脏以通过细胞保护途径减少梗死发展来预防心肌梗死诱导的心力衰竭。这些实验将使人们能够更好地了解一种潜在的有益的治疗蛋白质，这种蛋白质既可以预防急性细胞毒性，也可以促进MI后的功能改善。

 DESCRIPTION (provided by applicant): The loss of cardiac output immediately post-myocardial infarction (MI) triggers longer-term cardiac remodeling. MI remodeling consists of a loss of contractility and ventricular dilation leading to heart failure (HF). Strategies that maintin higher systolic function post-MI may circumvent the stimulus that ultimately leads to HF. One potential therapeutic target is Rad, a small GTPase that acts as a regulator of the L-type calcium channel; Rad loss promotes greater inward current, higher twitch calcium levels, greater fractional shortening of ventricular myocytes, and increased heart contractility. It is hypothesize that this improvement in calcium homeostasis and contraction can mitigate the loss of contractility post-MI. To test this hypothesis, Rad null mice will be subjected to coronary artery ligation, and serial echocardiography to monitor heart dimensions and function. Scar size will be evaluated using histology, and cytosolic calcium will be measured in stimulated isolated ventricular myocytes to determine if Rad null mice are protected from MI-induced calcium dysregulation, preventing loss of transient amplitude and the slowing of reuptake into the SR. In addition, the hypothesis that Rad null mice are protected from acute MI-induced necrosis and apoptosis will be tested using isolated perfused hearts subjected to ischemia, which will subsequently be stained and analyzed for infarct development. These results will also be investigated in vivo using late gadolinium enhanced MRI. It is hypothesized that deletion of Rad GTPase will prevent MI-induced heart failure through both preservation of cardiac output post-MI, and through the priming of the heart to reduce infarct development through cytoprotective pathways. These experiments will enable a better understanding of a potentially beneficial therapeutic protein that may both prevent acute cytotoxicity, as well as promote functional improvement after MI.