Metabolic Oscillations in Heart

描述（由申请人提供）：能量产生与能量需求的有效耦合对于跳动的心脏至关重要，破坏这种关系的因素可能会促进损伤。糖酵解振荡在酵母和胰腺中有广泛的特征。细胞，但促进其在心肌细胞中发生的条件较少建立，与活性氧（ROS）诱导的线粒体网络产生的代谢振荡相比。我们在兔心室肌细胞中的初步研究表明，正常情况下，氧化磷酸化和肌酸激酶（CK）穿梭对ATP/ADP比率的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敏感性K通道产生的大尺度动作电位时程（APD）振荡，在90%的心肌细胞中出现，正如理论预测的那样。在这个多PI提案中，我们的目标是结合联合收割机实验和数学生物学方法来解决两个问题：1）糖酵解振荡是如何调节/调节的生理因素，如Cai循环，自主紧张，胰岛素，和信号通路相关的心脏保护？2)在氧化磷酸化和CK穿梭缓冲细胞ATP/ADP比率的能力明显受损的急性心肌缺血期间，是否发生糖酵解振荡？这些问题将在三个具体目标中得到解决，这些目标将计算机模拟和非线性动力学与实验性膜片钳和成像研究结合起来，对来自兔、野生型和遗传修饰小鼠以及接受盖片缺血的新生大鼠心室肌细胞单层的分离肌细胞进行研究/再灌注。此外，一种新的荧光生物探针设计的ATP亚细胞成像将进一步发展，研究代谢动力学。这些研究将增加我们对代谢应激期间心脏代谢在系统水平上如何发挥作用的理解，这可能会导致对预防缺血/再灌注损伤的新的治疗见解。公共卫生相关性：由于心脏病是工业化社会的主要死亡原因，因此了解如何保护心脏免受损伤对NIH/NHLBI的卫生保健使命和整个社会都有重要意义。为了促进这种理解，这个跨学科的项目将整合实验生理学和数学生物学，研究糖酵解振荡的病理生理学，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关键情况下将能量产生与能量需求脱钩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，以保护心脏在代谢应激（如心脏病发作）期间免受损伤。

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.