Understanding the role of mitochondrial dysfunction in cardiac arrhythmias using a novel 3D panoramic optical mapping system

摘要 心律失常是发病率和死亡率的主要原因，由于年龄的增长，心律失常越来越普遍。 患有糖尿病、心力衰竭和高血压的人群。房颤(AF)和室颤(VF) 房性心动过速(AT)、心房扑动(AFL)和室性心动过速(VT) 更有组织、局灶性或大范围折返性心律失常。我们对具体机制的把握，使 保存有组织和/或混乱节律的心脏基础是不完整的。心律失常的致病因素 包括纤维化、晚期钠电流增加和反应性氧化应激(ROS)增加 有丝分裂，这是一个消除有缺陷的线粒体以维持整体健康的过程 线粒体池。我们在方法上的突破是使用3D全景解剖和光学标测， 结合有丝分裂检测来表征电激活、底物之间的相互作用 由于纤维化和有丝分裂引起的异质性，以及动作电位时程的异质性。我们的建议 概念是更大或更多数量的纤维化区，动作电位图的异质性和/或有丝分裂，将允许 更多混乱的房性或室性心律失常。通过单独扰乱这些途径并定义 对心律失常的影响，我们将确定这三个过程是如何共同调节的或 在功能上相互依赖。我们将老鼠与一种检测有丝分裂吞噬的报告基因Keima蛋白进行了杂交 与两个自发性和持续性房颤、房颤、AT、VT和VF转基因小鼠相比， 人类心脏NaV1.5通道基因SCN5A。该项目提出了一种综合的实验方法。 应用(1)房颤、室速、室颤等钠超负荷模型小鼠全心的多模式成像 或心肌梗死导致VT/VF了解有组织和混乱的心房和 室性心律失常的发生，(2)AAV递送线粒体过氧化氢酶逆转线粒体吞噬增加 心肌梗死和(3)通过AAV将视紫红质-2通道传递到整个小鼠心脏的光遗传学 使用聚焦光刺激来触发、预防和终止房性和室性心律失常。建议数 实验是非常有意义和创新的，因为联合注册的3D全景成像将使我们能够 剖析导致有组织和混乱的心律失常的机制，这可能导致新的和 心律失常的有效治疗策略。

ABSTRACT Cardiac arrhythmias are a major cause of morbidity and mortality, and are increasingly prevalent due to an aging population with diabetes, heart failure and hypertension. Atrial fibrillation (AF) and ventricular fibrillation (VF), are chaotic arrhythmias, whereas, atrial tachycardia (AT), atrial flutter (AFL) and ventricular tachycardia (VT) are more organized, focal or macro-reentrant arrhythmias. Our grasp of the specific mechanisms that allow for the cardiac substrate to harbor organized and/or chaotic rhythms is incomplete. Causative factors of arrhythmias include fibrosis, increased late Na+ current and increased reactive oxidative stress (ROS) causing augmented mitophagy, which is a process of eliminating defective mitochondria to maintain the overall health of the mitochondrial pool. Our methodological breakthrough is to use 3D panoramic anatomical and optical mapping, in conjunction with mitophagy detection to characterize the interplay amongst electrical activation, substrate heterogeneity due to fibrosis and mitophagy, and action potential duration (APD) heterogeneity. Our proposed concept is that larger or greater number of areas of fibrosis, APD heterogeneity and/or mitophagy will allow for more chaotic atrial or ventricular arrhythmias. By individually disrupting these pathways and defining the consequences on arrhythmogenesis, we will determine how these three processes are co-regulated or functionally inter-dependent. We crossed mice with a reporter Keima protein which detects mitophagy, together with two lines of transgenic mice with spontaneous and sustained AF, AFL, AT, VT and VF due to mutations in the human cardiac NaV1.5 channel gene SCN5A. This project presents an integrated experimental approach using (1) multi-modality imaging of whole hearts of murine models of Na+ overload with AF, AFL, AT, VT and VF or myocardial infarction induced VT/VF to understand the mechanisms of organized and chaotic atrial and ventricular arrhythmogenesis, (2) AAV delivery of mitochondrial catalase to reverse increased mitophagy after myocardial infarction and (3) optogenetics via AAV delivery of channelrhodopsin-2 into whole murine hearts and use of focused light stimulation to trigger, prevent and terminate atrial and ventricular arrhythmias. The proposed experiments are highly significant and innovative in that co-registered 3D panoramic imaging will allow us to dissect the mechanisms that drive organized and chaotic cardiac arrhythmias, which may lead to new and effective treatment strategies of cardiac arrhythmias.