Metabolic Oscillations in Heart

描述（由申请人提供）：能量生产与能量需求的有效耦合对心脏跳动至关重要，破坏这种关系的因素可能会导致损伤。糖酵解振荡在酵母和胰腺中广泛存在。但与活性氧（ROS）诱导的线粒体网络引起的代谢振荡相比，心肌细胞中促进其发生的条件较少建立。我们对兔心室肌细胞的初步研究表明，氧化磷酸化和肌酸激酶（CK）穿梭对ATP/ADP比率的正常紧密缓冲阻止了糖酵解振荡，但在这种缓冲被破坏的条件下，糖酵解振荡，表现为通过激活ATP敏感的K通道而产生的大规模动作电位持续时间（APD）振荡，在90%的心肌细胞中发展，正如理论预测的那样。在这个多pi提案中，我们的目标是结合实验和数学生物学方法来解决两个问题：1)糖酵解振荡是如何被生理因素（如Cai循环、自主神经紧张、胰岛素和与心脏保护相关的信号通路）调节的？2)急性心肌缺血期间是否发生糖酵解振荡，其中氧化磷酸化和CK穿梭缓冲细胞ATP/ADP比率的能力明显受损？这些问题将在三个特定目标中得到解决，这些目标将计算机模拟和非线性动力学与实验膜片钳和成像研究结合起来，这些研究来自兔，野生型和转基因小鼠和新生大鼠心室肌细胞单层受到复盖性缺血/再灌注。此外，一种新型的用于ATP亚细胞成像的荧光生物探针将进一步开发，以研究代谢动力学。这些研究将增加我们对代谢应激时心脏代谢如何在系统水平上起作用的理解，这可能会为预防缺血/再灌注损伤带来新的治疗见解。公共卫生相关性：由于心脏病是工业化社会中死亡的主要原因，了解如何保护心脏免受伤害对NIH/NHLBI的卫生保健使命和整个社会具有重大意义。为了促进这一认识，本跨学科项目将结合实验生理学和数学生物学来研究糖酵解振荡的病理生理学，糖酵解是缺血期间能量产生的关键代谢途径，以及它们如何通过在这种危急情况下将能量产生与能量需求分离来促进缺血性心脏损伤。这些见解可能会提出新的治疗方法来保护心脏免受代谢压力（如心脏病发作）的伤害。

DESCRIPTION (provided by applicant): Efficient coupling of energy production to energy needs is critical for the beating heart, and factors disrupting this relationship are likely to promote injury. Glycolytic oscillations have been characterized extensively in yeast and pancreatic ?-cells, but conditions promoting their occurrence in cardiac myocytes are less established, compared to reactive oxygen species (ROS)-induced metabolic oscillations arising from the mitochondrial network. Our preliminary studies in rabbit ventricular myocytes show that the normally tight buffering of the ATP/ADP ratio by oxidative phosphorylation and the creatine kinase (CK) shuttle prevents glycolysis from oscillating, but under conditions in which this buffering is disrupted, glycolytic oscillations, manifested as large scale action potential duration (APD) oscillations via activation of ATP-sensitive K channels, develop in 90% of cardiac myocytes, as predicted by theoretical predictions. In this multi-PI proposal, our goal is to combine experimental and mathematical biology approaches to address two questions: 1) how are glycolytic oscillations regulated/modulated by physiological factors such as Cai cycling, autonomic tone, insulin, and signaling pathways relevant to cardioprotection? 2) do glycolytic oscillations occur during acute myocardial ischemia, in which the ability of oxidative phosphorylation and the CK shuttle to buffer cellular ATP/ADP ratio is markedly compromised? These questions will be addressed in three Specific Aims which integrate computer simulations and nonlinear dynamics with experimental patch-clamp and imaging studies in isolated myocytes from rabbits, wild-type and genetically-altered mice and neonatal rat ventricular myocyte monolayers subjected to coverslip ischemia/reperfusion. In addition, a novel fluorescent bioprobe designed for subcellular imaging of ATP will be further developed to study metabolism dynamics. These studies will increase our understanding of how cardiac metabolism functions at the systems level during metabolic stress, which may lead to new therapeutic insights towards preventing ischemia/reperfusion injury. PUBLIC HEALTH RELEVANCE: Since heart disease is the major cause of death in industrialized societies, understanding how to protect the heart from injury has major implications for the health care mission of the NIH/NHLBI and for society as a whole. To facilitate this understanding, this interdisciplinary project will integrate experimental physiology and mathematical biology to study the pathophysiology of oscillations in glycolysis, the key metabolic pathway for energy production during ischemia, and how they may contribute to ischemic cardiac injury by uncoupling energy production from energy needs in this critical situation. These insights may suggest novel therapies to protect the heart from injury during metabolic stresses such as heart attacks.