Control of Local Calcium Signaling in the Heart

描述(申请人提供)：每一次心跳都需要协调每个心脏细胞的电兴奋和机械收缩，这一过程需要进入细胞的相对少量的钙(Ca)才能触发从肌浆网(SR)释放更多的钙。在健康的心脏中，这种钙诱导的钙释放(CICR)过程令人惊讶地稳定，尽管它依赖于正反馈。然而，CICR的错误调控最近被证明在心力衰竭等疾病状态中发挥着核心作用。尽管已经了解了相当多关于钙释放的基本单位-钙火花是如何被触发的，但关于这些事件是如何终止的，或者是否有缺陷的终止在疾病中发挥了作用，人们知之甚少。这项建议的目标是研究钙火花终止的基本分子机制，以及这些事件的终止如何影响CICR的调节。这项提议的目的将是进行关键的实验测试，以解决关于钙火花是如何触发以及如何终止的几个基本问题。 为了实现这一建议的特定目的，将在从大鼠和兔心脏分离的单个心室肌细胞上进行实验。这些细胞中钙浓度的亚细胞变化将通过荧光指示器和共聚焦显微镜进行跟踪。基于PI以前的工作的计算机建模将被用于解释数据和发展假设。 这项工作将提供关于正常心脏中钙是如何调节的基本新信息。这可以为更好地理解钙在疾病中如何被错误调节提供基础。因此，这项工作符合PI的长期目标，即了解健康和患病心脏中的电和化学信号。

DESCRIPTION (provided by applicant): Each heartbeat requires the coordination of electrical excitation and mechanical contraction in every heart cell, a process that requires a relatively small amount of calcium (Ca) entering the cell to trigger a much larger release of Ca from the sarcoplasmic reticulum (SR). In healthy hearts, this process of Ca-induced Ca release (CICR) is surprisingly stable despite the fact that it relies on positive feedback. However, mis-regulation of CICR has recently been shown to play a central role in disease states such as heart failure. Although a considerable amount has been learned about how the elementary units of Ca release, Ca sparks, are triggered, very little is known about how these events terminate or whether defective termination plays a role in disease. The goal of this proposal is to investigate fundamental molecular mechanisms by which Ca sparks terminate and how the termination of these events affects the regulation of CICR. The aims of this proposal will be to perform critical experimental tests that address several fundamental unanswered questions regarding how Ca sparks are triggered and how they terminate. To accomplish the Specific Aims of this proposal, experiments will be performed on single ventricular myocytes isolated from rat and rabbit hearts. Sub-cellular changes in Ca concentration in these cells will be tracked with a fluorescent indicator and a confocal microscope. Computer modeling, based on the Pi's previous work, will be used to interpret data and develop hypotheses. This work will provide fundamental new information about how Ca is regulated in normal hearts. This can provide a foundation for better understanding how Ca can be mis-regulated in disease. This work therefore fits in with the Pi's long term objective of understanding electrical and chemical signaling in healthy and diseased hearts.