In-vivo Imaging of Calcium in the Heart

描述(申请人提供)：钙(钙)振荡是许多重要的细胞过程的基础，这些过程使器官功能得以实现，包括心脏收缩。钙离子处理的异常伴随着大多数类型的心脏病理，并可能导致室性功能障碍和心律失常。这项建议旨在开发一种新的成像技术来研究活体动物钙瞬变的空间和时间异质性。我们将使用腺相关病毒血清型9(AAV-9)将GCaMP2稳定地运送到活动物的心脏，GCaMP2是最近开发的一种遗传编码的钙敏感分子。然后将使用光纤探头(光学电极)来连续评估开胸和闭胸动物的多个跨壁部位的钙离子浓度。我们将验证这一假设，即病理状态下跨室壁钙瞬变的变化有助于心脏功能障碍和心律失常的发展。在具体目标1中，将在结扎冠状动脉左前降支的过程中，研究开胸兔缺血再灌注模型中钙离子瞬变的急性变化。在特定的目标2中，将研究起搏引起的心力衰竭狗的钙瞬变的慢性变化。这些对心脏多个部位的原位钙瞬变的时间和空间测量将有助于深入了解在缺血和心力衰竭的情况下，异常的钙处理导致心功能障碍和心律失常的机制。公共卫生相关性：心脏病发作和心力衰竭仍然是美国疾病和过早死亡的主要原因。钙在每次心跳时触发收缩，在心脏病发作和心力衰竭后，钙调节是异常的。在这项提案中，我们将开发一种方法来测量活着的动物心脏细胞中的钙浓度，并使用这项技术来更好地了解钙的异常如何导致心力衰竭和猝死。

DESCRIPTION (provided by applicant): Calcium (Ca2+) oscillations underlie many important cellular processes that enable organ function, including contraction in the heart. Abnormalities in Ca2+ handling accompany most types of cardiac pathology, and may contribute to both ventricular dysfunction and arrhythmias. This proposal is aimed at developing a novel imaging technology to study spatial and temporal heterogeneities in Ca2+ transients in living animals. We will use adeno-associated virus serotype 9 (AAV-9) to stably deliver GCaMP2, a recently developed genetically encoded Ca2+-sensing molecule, into the hearts of living animals. Fiber optical probes (optrodes) will then be used to serially assess Ca2+ concentration at multiple transmural sites in both open- and closed-chest animals. We will test the hypothesis that transmural variation in Ca2+ transients during pathological states contributes to the development of cardiac dysfunction and arrhythmias. In Specific Aim 1, acute changes in Ca2+ transients will be studied in an open-chest rabbit model of ischemia-reperfusion during ligation of the left anterior descending coronary artery. In Specific Aim 2, chronic changes in Ca2+ transients will be studied in dogs with pacing-induced heart failure. These temporal and spatial measurements of in-situ Ca2+ transients at multiple sites in the heart will provide insights into the mechanisms by which abnormal Ca2+ handling contributes to cardiac dysfunction and arrhythmias in the setting of ischemia and heart failure. PUBLIC HEALTH RELEVANCE: Heart attacks and heart failure remain leading causes of illness and premature death in the United States. Calcium triggers the contraction during each heart beat, and calcium regulation is abnormal after a heart attack and in heart failure. In this proposal, we will develop a method to measure calcium concentrations in the heart cells of living animals and use this technology to better understand how abnormalities in calcium contribute to heart failure and sudden death.