Calcium signaling and cardiac arrhythmias

心律失常是人类死亡的主要原因，发生在多种情况下。提出的研究旨在确定和描述致命心律失常的基本机制。将检查触发心律失常的特定细胞和分子事件，以验证亚细胞钙信号的变化有助于心律失常发生的假设。心脏电活动改变的动物模型将在单细胞水平上使用全膜片钳方法和共聚焦钙成像进行研究。从对照动物和转基因动物分离的心肌细胞以及表达特定结构的细胞将用于计划的工作。初步结果表明，改变的电行为和特定细胞蛋白的表达之间存在钙依赖性联系，这些联系正在项目1 （Russo）、项目2 （Marks）和项目3 （Kass）中进行研究。特别感兴趣的蛋白包括beta1AR， beta2AR, RyR2, FKB12, FKBP12.6， SCN5A和这些蛋白的突变。提出的工作考察了靶蛋白的表达如何影响细胞内[Ca2+]i和Ca2+依赖性膜电流。本研究将探讨在提出的实验模型中，动作电位形状和持续时间对[Ca2+]i信号传导的重要性。此外，SR Ca2+含量和Ca2+释放之间的关系（通过Ca2+火花和全局（Ca2+）瞬态测量）将通过这些分子模型进行检查。因此，本项目中进行的实验应该为β - aar信号系统、肌层离子通道和细胞内Ca2+释放通道所起的心律失常作用提供基本的新信息。

Cardiac arrhythmias are a leading cause of death in humans and occur in diverse conditions. The proposed research seeks to identify and characterize fundamental mechanisms that underlie fatal cardiac arrhythmias. Specific cellular and molecular events that trigger arrhythmias will be examined to test the hypothesis that changes in subcellular calcium signaling contribute to arrhythmogenesis. Animal models of altered electrical activity in the heart will be studied at the single cells level using whole patch clamp methods and confocal calcium imaging. Isolated cardiac myocytes from control and transgenic animals and cells expressing specific constructs will be used in the planned work. Preliminary results have demonstrated calcium-dependent links between altered electrical behavior and the expression of specific cellular proteins that are being examined in Project 1 (Russo), Project 2 (Marks) and Project 3 (Kass). The proteins of particular interest include beta1AR, beta2AR, RyR2, FKB12, FKBP12.6, SCN5A and mutations of these proteins. The proposed work examines how expression of the target proteins affects intracellular [Ca2+]i and also Ca2+-dependent membrane currents. This examination will explore the importance of the action potential shape and duration on [Ca2+]i signaling in the proposed experimental models. Additionally the relationship between SR Ca2+ content and Ca2+ release (as measured by Ca2+ sparks and the global (Ca2+) transient) will be examined with these molecular models. The experiments carried out in this project should thus provide fundamental new information on the arrhythmogenic roles played by the betaAR signaling system, sarcolemmal ion channels and the intracellular Ca2+ release channels.