Calcium Signaling in Cardiac Excitation-Contraction

这项研究将主要在斯洛伐克共和国进行，作为NIH的延伸 授权号RO1HL52620。 这项提案的总体目标是阐明钙的机制， 哺乳动物心肌细胞二分体中的信号传导。这些结构， 代表兴奋-收缩偶联单位，包含L型簇 钙通道（兴奋单位）与兰尼碱簇并置 受体钙释放通道（释放单位）功能性偶联， 钙离子。 前馈钙信号传导步骤对于激活 通过兴奋释放钙，反馈钙信号步骤是 对钙电流和钙释放失活重要， 与兴奋-收缩耦合中通道拓扑结构的关系 单位将确定。为此，测量的动力学， 全细胞钙电流，全细胞钙瞬变，和二进 刺激期间和失活恢复期间的钙释放事件 将被执行。激发-收缩耦合的性质 单位，如钙通道门控和渗透，活性的分数 钙通道，以及钙与兰尼碱受体结合的速率， 会被操纵。钙电流动力学的定量分析 和平行的钙释放将用于估计钙的参数 信号对控制级配和效率至关重要， 兴奋-收缩偶联信道实验的计算机模拟 通过钙信号传导相互作用的簇将用于确定 可能的机制，并设计具有高预测能力的实验。 了解心脏E-C偶联的调节是重要的，因为它 可能成为心肌治疗干预的战略位点 功能障碍此外，确定钙基相互作用的机制 在共定位集群中的通道之间具有更广泛的意义， 了解突触传递、神经内分泌、 和调节血管张力。

This research will be done primarily in Slovak Republic as an extension of NIH grant # ROl HL52620. The overall goal of this proposal is to elucidate the mechanisms of calcium signaling in dyads of mammalian cardiac muscle cells. These structures, representing excitation-contraction coupling units, contain clusters of L-type calcium channels (the excitation unit) in apposition to clusters of ryanodine receptor calcium release channels (the release unit) functionally coupled by calcium ions. The feed-forward calcium signaling steps are important for activation of calcium release by excitation, the feedback calcium signaling steps are important for inactivation of calcium current and calcium release, and their relationship to the topology of channels in the excitation-contraction coupling unit will be determined. To this end, measurements of the kinetics of whole-cell calcium currents, whole-cell calcium transients, and dyadic calcium release events during stimulation and during recovery from inactivation will be carried out. The properties of the excitation-contraction coupling unit, such as calcium channel gating and permeation, the fraction of active calcium channels, and the rate of calcium binding to the ryanodine receptor, will be manipulated. Quantitative analysis of the kinetics of calcium current and calcium release in parallel will be used to estimate parameters of calcium signaling critical for control of gradation and efficiency of excitation-contraction coupling. Computer simulations of experiments on channel clusters that interact by way of calcium signaling will be used to ascertain possible mechanisms and to design experiments with high predictive power. Understanding the regulation of cardiac E-C coupling is important since it might become a strategic site for therapeutic intervention in cardiac muscle dysfunctions. Furthermore, defining mechanisms of calcium-based interaction between channels in co-localized clusters has a broader significance for understanding processes such as synaptic transmission, neuroendocrine secretion and regulation of vascular tone.