Suppression of cardiac calcium channels by acute hypoxia

急性缺氧对心脏钙通道的抑制

• 批准号: 8301587
• 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 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8301587
• 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.

描述(申请人提供)：在工作心肌中，急性血流阻塞之后，氧分压会迅速下降，几分钟内就会造成不可逆转的组织损伤。缺血性脑梗塞的发生是一系列的事件，包括细胞水平的能量产生减少(-AMP，/ATP，-脑分解，/pH，-ROS)，离子通道活性改变(/ICa，-[K+]o，-[Na+]i)，以及钙信号受损(/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，心肌缺氧的开始(&lt；60 S)首先被钙通道调节机制检测到，导致通道电流的快速抑制早在全球细胞代谢表现(/ATP、/pH、-ROS等)之前很久。为了验证这一假说，我们将在单个心肌细胞上进行实验，使其暴露在氧分压阶跃变化中，同时使用电压钳和钙成像技术监测ICa和[Ca2+]i。PO2的变化将通过快速灌流系统(&lt；50ms)实施，并将在细胞附近进行监测。其具体目的是：1)表征急性缺氧时抑制ICA的离子、电压和磷酸化依赖；2)确定检测氧丢失的分子实体和导致钙通道调节的信号通路。意义和影响：拟议的研究可能与心脏缺氧性缺血期患者的治疗直接相关。这一结果可能确立低氧诱导的ICA抑制是保存代谢能量和延缓钙超载的固有第一道防线。从更广泛的角度来看，重要的是梳理由低氧触发和/或汇聚的各种调控通路，以控制ICA、收缩力量和ATP的支出。反过来，认识到这些通路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方案，例如，在再灌流开始时，抑制ICA已被临床用于预防随后的心律失常。如果所提出的氧气传感器确实对钙离子通道的控制做出了重大贡献，它可能会导致新一类治疗心脏损伤的疗法的开发。创新：这是一个新的想法，即急性缺氧对ICA的抑制可以在细胞能量代谢、离子梯度和氧化还原状态发生显著变化之前很久就由快速调节途径触发。为了测试这一想法，我们使用了一系列电生理、光学和分子技术，这些技术提供了关键信号参数的同时测量，并适合于动力学研究。为了探索临床相关性，我们将扩大实验范围，从标准的动物模型扩展到包括可用的人类心肌细胞和来自右、左心室的细胞。