Calcium Signaling, Metabolism, and EC Coupling in Heart

项目摘要/摘要 申请者S的长期目标是继续研究钙信号、兴奋收缩(EC)。 偶联，以及这些过程对心肌能量代谢的依赖。具体目标 是为了研究兔和小鼠的心室细胞(包括心脏特异的钠钙交换器 基因敲除小鼠)以：1)研究梗塞周围重塑细胞中的钙信号和EC偶联 兔的带状突起。这将包括评估L型钙通道功能丧失是否可以 解释EC偶联失败的原因以及横管、兰诺定和 二氢吡啶受体参与了这些细胞的衰竭；2)研究代谢的影响 抑制兔心室肌细胞偶联蛋白的功能和结构。这将包括一个 一联L型钙通道最小数目及代谢途径的测定 抑制会影响它们的功能。特别是，钙火花和棘波的形成以及细胞微结构的变化 横管系统是代谢过程中偶联蛋白功能丧失的原因 3)研究钠钙交换基因敲除小鼠对代谢的抵抗力 压力。这将包括对代谢抑制阻止激活的假设的调查 逆转野生型小鼠钠钙交换，导致钙诱导的钙离子交换中断 EC联轴器的释放机理。相反，假设钠钙交换基因敲除 小鼠不需要钠钙交换来进行EC偶联，因此对 代谢抑制。抑制钠钙交换激活对钙离子峰值的影响 将检查延迟。这些实验的目的之一是解释 在触发过程中发生钙离子双向裂解。方法包括测量钙峰概率和它们的 代谢抑制剂治疗前后兔和小鼠的潜伏期分布。此外， 方法包括最近开发的重建建筑的三维结构的程序 大鼠横管系统与兰尼定和二氢吡啶受体的三维分布 梗塞周围细胞和代谢抑制剂处理的细胞。

Project Summary/Abstract The applicant¿s long-term aims are to continue studies on calcium signaling, excitation-contraction (EC) coupling, and the dependence of these processes on energy metabolism in cardiac muscle. The specific aims are to study ventricular cells from rabbits and mice (including cardiac-specific sodium-calcium exchanger knock-out mice) to: 1) investigate calcium signaling and EC coupling in remodeled cells from the peri-infarct zone in rabbits. This will include an assessment of whether loss of L-type calcium channel function can account for failure of EC coupling and whether significant alterations in transverse-tubules, ryanodine and dihydropyridine receptors are involved in the failure of these cells; 2) investigate the effect of metabolic inhibition on the function and structure of couplons in rabbit ventricular myocytes. This will include a measurement of the minimum number of L-type calcium channels in a couplon and the way that metabolic inhibition affects their function. In particular, alterations in calcium spark and spike formation and cellular microarchitecture of the transverse-tubule system as a cause of the functional loss of couplons during metabolic inhibition will be considered; 3) study the resistance of sodium-calcium exchanger knock-out mice to metabolic stress. This will include an investigation of the hypothesis that metabolic inhibition prevents activation of reverse sodium-calcium exchange in wild-type mice, resulting in disruption of the calcium-induced calcium release mechanism of EC coupling. In contrast, it is hypothesized that sodium-calcium exchanger knock-out mice do not require sodium-calcium exchange for EC coupling and are therefore resistant to the effects of metabolic inhibition. The consequences of inhibiting sodium-calcium exchange activation on calcium spike latency will be examined. These experiments are, among other things, designed to explain the importance of diadic cleft calcium in the trigger process. Methods include measuring calcium spike probabilities and their latency distributions in rabbits and mice before and after treatment with metabolic inhibitors. In addition the methods include recently developed procedures for reconstructing the 3-dimensional architecture of the transverse¿tubule system and the 3-dimensional distribution of ryanodine and dihydropyridine receptors in peri-infarct cells and cells treated with metabolic inhibitors.