Control of Local Calcium Signaling in the Heart

描述（由申请人提供）：每次心跳需要每个心脏细胞中的电兴奋和机械收缩的协调，这是一个需要相对少量的钙（Ca）进入细胞以触发肌浆网（SR）大量释放Ca的过程。在健康的心脏中，钙诱导的钙释放（CICR）过程是惊人的稳定，尽管它依赖于正反馈。然而，CICR的错误调节最近已被证明在疾病状态如心力衰竭中发挥核心作用。虽然已经了解了相当多的关于钙释放的基本单位，钙火花，是如何触发的，很少有人知道这些事件如何终止或是否有缺陷的终止在疾病中发挥作用。本提案的目标是研究Ca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。该提案的目的是进行关键的实验测试，以解决有关钙火花如何触发以及如何终止的几个基本未回答的问题。 为了实现本提案的特定目的，将对从大鼠和家兔心脏分离的单个心室肌细胞进行实验。用荧光指示剂和共聚焦显微镜跟踪这些细胞中Ca浓度的亚细胞变化。计算机建模，基于Pi以前的工作，将用于解释数据和发展假设。 这项工作将提供有关钙在正常心脏中如何调节的基本新信息。这可以为更好地理解Ca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信号和化学信号。

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.