Suppression of cardiac calcium channels by acute hypoxia

急性缺氧对心脏钙通道的抑制

• 批准号: 8086360
• 负责人: MARTIN MORAD
• 金额: $ 34.25万
• 依托单位: UNIVERSITY OF SOUTH CAROLINA AT COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-15 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8086360
• 关键词: Acidosis; Acute; Address; Adrenergic Agents; Affect; Animal Model; Animals; Arrhythmia; Blood; Blood Vessels; Blood flow; Brain Hypoxia-Ischemia; Calcium Channel; Cardiac; Cardiac Myocytes; Cardiomyopathies; Cells; Chronic; Coronary Thrombosis; Coronary artery; Coupling; Cyclic AMP-Dependent Protein Kinases; Dependence; Development; Dihydropyridines; Dilatation - action; Disease Management; Dose; Drops; Electrodes; Energy Metabolism; Event; Expenditure; Glycolysis; Heart; Heart Atrium; Heart Hypertrophy; Heart failure; Human; Husband; Hyponatremia; Hypoxia; Imaging Techniques; Infarction; Injury; Ion Channel; Ischemia; Kinetics; Lead; Left; Left ventricular structure; Literature; Measurement; Measures; Metabolic; Mitochondria; Modification; Molecular; Monitor; Myocardium; Neuraxis; Optics; Oxidation-Reduction; Oxygen; Oxygen measurement, partial pressure, arterial; Pathway interactions; Patients; Perfusion; Phosphorylation; Play; Production; Proteins; Pulmonary Valve Insufficiency; Reflex action; Regulation; Regulatory Pathway; Reperfusion Therapy; Research; Resources; Right ventricular structure; Role; Signal Pathway; Signal Transduction; Sorting - Cell Movement; Staging; System; Techniques; Testing; Therapeutic; Tissues; Ventricular; Work; adrenergic; angiogenesis; base; calmodulin-dependent protein kinase II; clinically relevant; deprivation; dihydropyridine; genetic regulatory protein; heart cell; innovation; insight; novel; novel therapeutics; prevent; prophylactic; research study; response; sensor; treatment strategy; voltage; voltage clamp

DESCRIPTION (provided by applicant): In working myocardium, acute blockage of blood flow is followed by a rapid drop in oxygen tension that within minutes causes irreversible tissue damage. The onset of ischemic infarction is marked by a cascade of events that at the cellular level includes reduced energy production (-AMP, / ATP, -gycolysis, /pH, -ROS), altered ion channel activity (/ICa, -[K+]o, -[Na+]i), and impaired Ca2+ signaling (/ICa, -diastolic [Ca2+]i) leading eventually to arrhythmia, cardiomyopathy, and heart failure. We hypothesize that the onset of cardiac hypoxia (<60 s) is first detected by a Ca2+ channel regulatory mechanisms leading to rapid channel current suppression long before the global cellular metabolic manifestations (/ATP, /pH, -ROS etc.). To test this hypothesis, we shall perform experiments on single cardiomyocytes exposed to step changes in oxygen tension while ICa and [Ca2+]i are monitored using voltage-clamp and Ca2+-imaging techniques. The changes in pO2 will be implemented with a rapid perfusion system (<50 ms), and will be monitored in the immediate vicinity of the cells. The specific aims are: 1) To characterize the ionic-, voltage-, and phosphorylation- dependence of suppression of ICa in response to acute hypoxia, and 2) To identify the molecular entity that detects the loss of oxygen and the signaling pathway that leads to the modulation of the Ca2+ channel. Significance and Impact: The proposed research might be directly relevant to the management of patients who suffer periods of cardiac hypoxic ischemia. The results may establish hypoxia-induced suppression of ICa as an inherent first line of defense that preserves metabolic energy and delays Ca2+ overload. In a wider perspective, it is important to sort out the various regulatory pathways that are triggered by hypoxia and/or converge to control ICa, force of contraction, and expenditure of ATP. In turn, recognition of the independence or interdependence of these pathways may serve to identify prophylactic and therapeutic options that are relevant to all stages of acute and chronic cardiac hypoxia including e.g. the onset of reperfusion where suppression of ICa is already clinically used to prevent ensuing arrhythmias. If the proposed O2 sensor does indeed contribute significantly to the control of the Ca2+ channel, it may lead to development of new class of therapeutics for treatment of cardiac injury in general. Innovation: It is a novel idea that the suppression of ICa by acute hypoxia can be triggered by a rapid regulatory pathway long before significant occurrence of changes in the cellular energy metabolism, ionic gradients and redox state. To test this idea, we use an array of electrophysiological, optical, and molecular technique that provide simultaneous measurements of key signaling parameters and are suited for kinetic studies. To explore clinical relevance we shall expand the experimental scope from standard animal models to also include available human cardiac cells and cells from the right and left ventricles. PUBLIC HEALTH RELEVANCE: The human heart suffers irreversible damage when its supply of oxygenated blood is interrupted even briefly by coronary thrombosis. We shall explore an inherent, potentially protective, mechanism whereby heart cells sense oxygen deprivation and respond rapidly to husband their energy resources by down-regulating their calcium channels, which are essential in maintaining the rhythm and strength of the heart beat. This project may provide insight into the multi-faceted function of one of the key proteins of the heart, and help us identify the oxygen sensor of the heart and develop new therapeutic strategies for treatment of the diseased heart.

描述（由申请人提供）：在工作心肌中，血流急性阻塞后，氧张力迅速下降，几分钟内就会导致不可逆的组织损伤。缺血性梗塞的发作以细胞水平上的一系列事件为标志，包括能量产生减少（-AMP、/ATP、-糖分解、/pH、-ROS）、离子通道活性改变（/ICa、-[K+] o，-[Na+]i）和 Ca2+ 信号传导受损（/ICa，-舒张期 [Ca2+]i）最终导致心律失常、心肌病和心力衰竭。我们假设心脏缺氧（<60 s）的发生首先由 Ca2+ 通道调节机制检测到，导致通道电流快速抑制，早在整体细胞代谢表现（/ATP、/pH、-ROS 等）之前。为了检验这一假设，我们将对暴露于氧张力阶跃变化的单个心肌细胞进行实验，同时使用电压钳和 Ca2+ 成像技术监测 ICa 和 [Ca2+]i。 pO2 的变化将通过快速灌注系统（<50 ms）实现，并将在细胞附近进行监测。具体目标是：1) 表征急性缺氧时 ICa 抑制的离子依赖性、电压依赖性和磷酸化依赖性，以及 2) 确定检测氧丢失的分子实体以及导致氧丢失的信号通路对 Ca2+ 通道的调节。意义和影响：拟议的研究可能与心脏缺氧缺血期患者的治疗直接相关。结果可能确定缺氧诱导的 ICa 抑制是保护代谢能量并延迟 Ca2+ 超载的固有第一道防线。从更广泛的角度来看，理清由缺氧触发和/或汇聚以控制 ICa、收缩力和 ATP 消耗的各种调节途径非常重要。反过来，认识到这些途径的独立性或相互依赖性可能有助于确定与急性和慢性心脏缺氧的所有阶段相关的预防和治疗选择，包括例如心脏缺氧。再灌注开始时，抑制 ICa 已在临床上用于预防随后发生的心律失常。如果所提出的 O2 传感器确实对 Ca2+ 通道的控制做出了重大贡献，那么它可能会导致开发用于治疗一般心脏损伤的新型疗法。创新：这是一个新颖的想法，即早在细胞能量代谢、离子梯度和氧化还原状态发生显着变化之前，快速调节途径就可以触发急性缺氧对ICa的抑制。为了测试这个想法，我们使用了一系列电生理学、光学和分子技术，这些技术可以同时测量关键信号参数，并且适合动力学研究。为了探索临床相关性，我们将把实验范围从标准动物模型扩大到包括可用的人类心脏细胞以及来自右心室和左心室的细胞。 公共卫生相关性：当人类心脏的含氧血液供应因冠状动脉血栓形成而短暂中断时，心脏就会遭受不可逆转的损害。我们将探索一种固有的、潜在的保护机制，通过该机制，心脏细胞感知缺氧，并通过下调钙通道来快速响应以节省能量资源，钙通道对于维持心跳的节律和强度至关重要。该项目可以深入了解心脏关键蛋白质之一的多方面功能，并帮助我们识别心脏的氧传感器并开发治疗患病心脏的新治疗策略。