Molecular Approaches to Arrhythmia Therapy

该计划项目的目标是开发基于改进的抗心律失常的新方法 对导致心源性猝死的心律失常机制的理解。项目4将结合 生物实验和数学模型研究L型钙离子通道之间的相互作用 (L[钙，L})，钙瞬变和其他钙敏感电流导致正常人早期后除极(EADS) 和衰竭的心室肌细胞(目标1)。这一分析将被用来指导治疗的发展 通过改变I{Ca，L}特性抑制EADS和EAD介导的心律失常的策略(目标2)。我们会 利用动态膜片钳方法，允许添加虚拟电流并相互作用 与活的心肌细胞的内源性电流双向作用。EADS将由各种不同的 干预，然后用钙通道阻滞剂硝苯地平抑制。在各个阶段，动态夹具将 加回虚拟I{Ca，L}虚拟Ca；瞬变等钙敏感电流，确定所需 重组EADS所需的相互作用。鉴于I{Ca，L}窗口电流在EAD中的关键作用 ，我们将使用动态钳位方法来探索动力学和/或电压是如何依赖的 I{Ca，L}的性质可以被修饰，以抑制分离的心肌细胞中“重组”的EADS。正常的我{Ca，L} 动态夹具将被适当修改的虚拟I{Ca，L}替换，以识别哪些修改 消除EADS，同时保持正常的Ca{i}瞬变(目标2a)。利用这些信息，我们将探索 钙、L对兔心室肌细胞的遗传修饰以确定抑制EADS的干预措施 在不影响E-C偶联的情况下，使用两种策略：i)辅助细胞的遗传过表达 通道亚单位取代相应的天然钙通道亚单位。二)下调对本地钙的管制 使用合适的病毒载体在成年兔心肌细胞中的通道亚基。这些混血儿 模型/实验研究有望促进我们对EAD机制的理解 形成并确定新的抗心律失常策略。项目4将得到建模的补充 项目1的研究，P2的细胞水平研究，项目3的组织水平研究。

The goal of this Program Project is to develop novel antiarrhythmic approaches based on improved understanding of the arrhythmia mechanisms causing sudden cardiac death. Project 4 will combine biological experiments and mathematical modeling to study how the interaction between the L-type Ca curret (l{Ca,L}), the Ca{i} transient and other Ca-sensitive currents lead to early afterdepolarizations (EADs) in normal and failing ventricular myocytes (Aim 1). This analysis will then be used to guide development of therapeutic strategies to suppress EADs and EAD-mediated arrhythmias by modifying I{Ca,L} properties (Aim 2). We will utilize the dynamic patch clamp approach which permits virtual currents to be added and interact bidirectionally with the endogenous currents of a live myocyte. EADs will be induced with various interventions, and then suppressed by the Ca channel blocker nifedepine. In stages, the dynamic clamp will add back a virtual I{Ca,L} virtual Ca; transient, and other Ca-sensitive currents to determine the necessary interactions required to reconstitute EADs. Given the critical importance of the I{Ca,L} window current in EAD formation, we will use the dynamic clamp approach to explore how the kinetic and/or voltage dependent properties of I{Ca,L} can be modified to suppress "reconstituted" EADs in isolated myocytes. The normal I{Ca,L} in the dynamic clamp will be replaced with an appropriately modified virtual I{Ca,L} to identify which modifications eliminate EADs while preserving a normal Ca{i} transient (Aim 2a). Using this information, we will explore genetic modifications of I{Ca,L} in rabbit ventricular myocytes to identify interventions which suppress EADs without adversely affecting E-C coupling, using two strategies: i) genetic overexpression of ancillary Ca channel subunits to replace the corresponding native Ca channel subunits. ii) downregulation of native Ca channel subunits in the adult rabbit ventricular myocytes using appropriate viral vectors. These hybrid modeling/experimental studies promise to both advance our understanding of the mechanisms of EAD formation and identify novel antiarrhythmic strategies. Project 4 will be complemented by the modeling studies in Project 1, cellular level studies in P2, and tissue level studies in Project 3.