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; 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）：在工作心肌时，血流的急性阻塞后，氧气张力迅速下降，几分钟内会导致不可逆的组织损伤。 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,心肌病和心力衰竭。我们假设心脏缺氧（<60 s）的发作首先是由Ca2+通道调节机制检测到的，导致在全球细胞代谢表现（ /ATP， /pH，-ROS等）之前很久以来导致快速通道电流抑制。为了检验这一假设，我们将对暴露于氧气张力的步骤变化的单个心肌细胞进行实验，而ICA和[Ca2+] I使用电压钳和CA2+成像技术进行监测。 PO2的变化将通过快速的灌注系统（<50 ms）实施，并将在细胞附近进行监测。具体目的是：1）表征ICA对急性缺氧的抑制的离子，电压和磷酸化依赖性，以及2）确定检测氧损失的分子实体，以及导致CA2+通道调节的信号通路的损失和信号传导途径。意义和影响：拟议的研究可能与遭受心脏低氧缺血时期患者的管理直接相关。结果可能会确定缺氧引起的ICA作为固有的第一道防线抑制，从而保留代谢能量并延迟CA2+过载。从更广泛的角度来看，重要的是要弄清由缺氧和/或收敛以控制ICA，收缩力和ATP支出的各种调节途径。反过来，对这些途径的独立性或相互依赖性的认识可能有助于识别与急性和慢性心脏缺氧所有阶段有关的预防和治疗选择，包括例如在临床上已经使用了抑制ICA的再灌注开始，以防止心律不齐。如果所提出的O2传感器确实确实有助于控制Ca2+通道，则可能导致开发新的治疗疗法，以治疗心脏损伤。创新：这是一个新颖的想法，即通过急性缺氧对ICA的抑制可以通过快速的调节途径触发，早在细胞能量代谢，离子梯度和氧化还原状态的显着变化之前就可以触发。为了测试这个想法，我们使用一系列电生理，光学和分子技术，可同时测量关键信号参数，并适合动力学研究。为了探索临床相关性，我们应将实验范围从标准动物模型扩展到还包括可用的人类心脏细胞和左室和左心室细胞。 公共卫生相关性：当人类心脏的含氧血液供应甚至因冠状动脉血栓形成而短暂地中断时，人心脏会遭受不可逆转的损害。我们将探索一种固有的，潜在的保护性机制，心脏细胞通过下调其钙通道来感知氧气剥夺并迅速对丈夫的能源反应，这对于维持心脏的节奏和力量至关重要。该项目可以洞悉心脏关键蛋白质之一的多面功能，并帮助我们识别心脏的氧气传感器，并制定新的治疗策略来治疗患病心脏的心脏。