Calcium signaling and cardiac arrhythmias

心律失常是人类死亡的主要原因，并且发生在不同的条件下。拟议的研究旨在确定和表征致命性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，以检验亚细胞钙信号传导的变化有助于心律失常发生的假设。将使用全膜片钳方法和共聚焦钙成像在单细胞水平上研究心脏电活动改变的动物模型。在计划的工作中将使用来自对照和转基因动物的分离心肌细胞以及表达特定构建体的细胞。初步结果表明，改变的电行为和特定细胞蛋白质的表达之间存在钙依赖性联系，这些蛋白质正在项目1（Russo），项目2（Marks）和项目3（Kass）中进行研究。特别感兴趣的蛋白质包括β 1 AR、β 2 AR、RyR2、FKB 12、FKBP 12.6、SCN 5A和这些蛋白质的突变。拟议的工作检查如何表达的靶蛋白影响细胞内[Ca 2 +]i和Ca 2+依赖性膜电流。本研究将探讨动作电位的形状和持续时间对[Ca2+]i信号在拟议的实验模型的重要性。此外，SR Ca2+含量和Ca2+释放（通过Ca2+火花和全局（Ca2+）瞬态测量）之间的关系将与这些分子模型进行检查。因此，本项目中进行的实验应提供关于β AR信号系统、肌膜离子通道和细胞内Ca 2+释放通道所起的促炎作用的基本新信息。

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.