Investigate the effect of mitochondrial energy state on Ca2+ sparks and handling

描述（由申请人提供）：心脏病是美国人最大的单一杀手。越来越多的证据表明，Ca 2+处理异常与心脏病的发展之间存在密切关系。因此，了解病理条件下Ca 2+信号的调节至关重要。Ca 2+诱导的Ca 2+释放（CICR）的局部控制依赖于L-型Ca 2+通道和ryanodine受体（RyR）的空间结构。类似地，线粒体对Ca 2+的吸收是通过它们与Ca 2+释放位点的紧密接近而促进的，这是在工作变化期间刺激氧化磷酸化所需的过程。然而，线粒体对CICR的反馈还不太清楚。由于线粒体是活性氧（ROS）的主要来源，它们可能会影响细胞溶质的氧化还原状态，进而改变RyR开放概率。在这项拟议的研究中，双光子激光显微镜系统将被用来直接研究如何在各种实验条件下的能量状态的急剧变化动态影响钙离子火花特性。将在分离的豚鼠心肌细胞中同时记录细胞溶质Ca 2+（或ROS）、A2 m和NADH，并使用成像离线分析。线粒体之间的时空耦合！去极化和Ca 2+火花将使用定量方法进行分析。此外，我们还将建立一个线粒体和Ca 2+释放单元的计算模型，以定量研究线粒体能量学之间的相互作用 和局部Ca 2+处理。最后，一个整合模型的心肌细胞纳入基板 将开发代谢、细胞电生理学、pH调节和E-C偶联，以研究缺血-再灌注期间能量产生、离子通道、Ca 2+处理和pH的改变以及由此导致的心脏收缩功能降低的潜在机制。通过结合实验和计算结果，这些研究将允许完整地了解缺血后损伤的起源和心力衰竭的发展，并显着刺激新的心脏病治疗方法的发展。

DESCRIPTION(provided by applicant): Heart disease is the single largest killer of the American. A growing body of evidence has shown that there is a close relationship between Ca2+ handling abnormalities and development of heart disease. Therefore it is fundamentally important to understand the regulation of Ca2+ signaling under pathological conditions. Local control of Ca2+-induced Ca2+ release (CICR) depends on the spatial organization of L-type Ca2+ channels and ryanodine receptors (RyR) in the dyad. Analogously, Ca2+ uptake by mitochondria is facilitated by their close proximity to the Ca2+ release sites, a process required for stimulating oxidative phosphorylation during changes in work. Mitochondrial feedback on CICR, however, is less well understood. Since mitochondria are a primary source of reactive oxygen species (ROS), they could potentially influence the cytosolic redox state, in turn altering RyR open probability. In this proposed study, a two photon laser microscope system will be used to directly examine how acute changes in energy state dynamically influence Ca2+ spark properties under various experimental conditions. Cytosolic Ca2+ (or ROS), A^m, and NADH will be recorded simultaneously in isolated guinea pig cardiomyocytes and analyzed offline using imaged. The spatiotemporal coupling between mitochondria! depolarization and Ca2+ sparks will be analyzed using a quantitative approach. Furthermore, a computational model of mitochondria and Ca2+ release unit will be developed to quantitatively investigate the interaction between mitochondrial energetics and local Ca2+ handling. Finally, an integrated model of the cardiomyocyte incorporating substrate metabolism, cellular electrophysiology, pH regulation and E-C coupling will be developed to investigate the mechanisms underlying alterations in energy production, ion channels, Ca2+ handling and pH, as well as the resulting reduction of cardiac contractile function during ischemia-reperfusion. By combining the experimental and computational results, these studies will allow for a complete understanding the origin of post-ischemic injury and development of heart failure, and significantly spur the development of novel heart disease therapies.