Regulation of ion channels in the heart

描述（由申请人提供）： 心血管疾病是美国和退伍军人发病率和死亡率的主要原因。在上一个资助周期中，我们已经鉴定了几种心房特异性通道，包括Cav1.3（1D）L型Ca 2+通道和小电导Ca 2+激活的K+通道（SK或KCa 2通道），它们在心房肌细胞以及窦房（SA）和房室（AV）结的功能中起关键作用。具有临床意义的是，我们已经证明SK通道在人心房肌细胞中表达并显著促进复极过程。 对于目前的竞争更新应用程序，我们将集中精力在心室肌细胞和起搏细胞的钙离子通道的亚细胞调节。嵌入在我们的研究结果和拟议的项目是相关的范式转变，可以利用在开发特定的药物治疗心律失常。具体来说，我们将测试中心的假设，有亚型特异性的差异调节L-型钙电流在心室肌细胞和起搏细胞的腺苷酸环化酶（AC）的不同亚型。我们将利用新出现的活细胞成像技术，结合基于荧光共振能量转移（FRET）的cAMP和蛋白激酶A（PKA）传感器，直接破译不同的亚细胞定位和活性， 不仅在心室肌细胞中，而且在起搏细胞中也存在不同的AC亚型。事实上，我们将利用多学科技术，包括体内和体外电生理记录、活细胞成像和分子建模，来确定通过不同的AC亚型对Ca 2+通道的亚细胞调节。我们的研究将扩展我们对个体细胞的特异性亚细胞定位和调控的理解。 Ca 2+通道以及它们如何协调介导体内正常心律。了解心脏中Ca 2+通道的分子和亚细胞调节将为治疗心律失常和SA和AV结功能障碍的新的和更机械的方法奠定基础，这是我们退伍军人群体中遇到的常见问题。

DESCRIPTION (provided by applicant): Cardiovascular disease is the leading cause of morbidity and mortality in the United States and in our veteran population. During the last funding cycle, we have identified several atrial-specifi ion channels including Cav1.3 (1D) L-type Ca2+ channel and small conductance Ca2+-activated K+ channels (SK or KCa2 channels) which play critical roles in the function of atrial myocytes as well as sinoatrial (SA) and atrioventricular (AV) nodes. Of clinical importance, we have demonstrated that SK channels are expressed and contribute significantly to the repolarization process in human atrial myocytes. For the current competing renewal application, we will focus our effort on the subcellular regulation of Ca2+ channels in ventricular myocytes and pacemaking cells. Embedded in our findings and the proposed project are relevant paradigm shifts that may be exploited in developing specific drugs for the treatment of cardiac arrhythmias. Specifically, we will test the central hypothesis that there is isoform-specific differential regulation of L-type Ca2+ current in ventricular myocytes and pacemaking cells by distinct isoforms of adenylyl cyclases (ACs). We will utilize new emerging techniques of live-cell imaging coupled with fluorescence resonance energy transfer (FRET)-based cAMP and protein kinase A (PKA) sensors to directly decipher the distinct subcellular localization and activities of different isoforms of ACs not only in ventricular myocytes but also in pacemaking cells. Indeed, we will take advantage of multidisciplinary techniques including in vivo and in vitro electrophysiologic recordings, live-cell imaging, and molecular modeling to determine the subcellular regulation of Ca2+ channels through distinct isoforms of ACs. Our proposed studies will expand our understanding of the specific subcellular localization and regulation of individual Ca2+ channels and how they might coordinate to mediate normal cardiac rhythm in vivo. Understanding the molecular and subcellular regulation of Ca2+ channels in the heart will set the stage for a new and more mechanistic approach for the treatment of cardiac arrhythmias and SA and AV node dysfunction, a common problem encountered in our veteran population.