POST INFARCTION K CHANNEL REMODELING/MOLECULAR MECHANISM

梗塞后K通道重塑/分子机制

• 批准号: 6538058
• 负责人: Gea-Ny Tseng
• 金额: $ 32.63万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6538058
• 关键词: Xenopus oocyte; calcium ion; cardiac myocytes; dogs; electrophysiology; enzyme activity; heart ventricle; myocardial infarction; polymerase chain reaction; potassium channel; protein isoforms; protein kinase; protein structure function; voltage /patch clamp; western blottings

The long-long objectives of our research project are to understand the molecular basis for heterogeneity in K channel function in normal heart, and the mechanisms for alterations in K channel function in diseased heart. In normal heart, the pattern of K channel heterogeneity helps maintain the cardiac electrical stability. Perturbations of such normal heterogeneity will likely predispose the heart to arrhythmias. Such situation occurs in hypertrophied/failing hearts where alterations in K channel function contribute to a dispersion of repolarization, setting the stage for reentrant arrhythmias. To design effective therapies for these pathological conditions, it is important to know, at the molecular level, what causes such a normal pattern of K channel distribution and how it is perturbed in diseased heart. The focus of this proposal is the transient outward (Ito), slow delayed rectifier (IKs) and rapid delayed rectifier (IKr) currents, the three major repolarizing K currents in cardiac myocytes. We will use dog as our animal model, and compare K channel function in normal hearts and in hearts with chronic myocardial infarction where various remodeling processes have occurred. We will apply the techniques of electrophysiology, molecular biology, immunoblotting and immunocytochemistry to examine channel function and subunit expression. The strategy is to use an iterative process between experiments on native channels in cardiac myocytes and experiments on channel clones expressed in in vitro systems to establish a correlation between subunit composition and channel function. Four Specific Aims are proposed. Under the first 3 Aims, we will study why the current density and gating kinetics of Ito, IKs and IKr, respectively, are heterogeneous in normal heart. The information, as well as the tools (K channel subunit cDNAs and antibodies) we develop during these Aims, will be applied under Aim 4 to examine the molecular basis for K channel remodeling in postinfarction heart. Results from these experiments will provide new insights into molecular physiology and pathology of cardiac K channels, which will aid the design of therapeutic interventions for arrhythmias in postinfarction remodeled hearts.

本研究项目的长期目标是了解正常心脏K通道功能异质性的分子基础，以及疾病心脏K通道功能改变的机制。 在正常心脏中，K通道的异质性模式有助于维持心脏电稳定性。 这种正常异质性的扰动可能使心脏易患心律失常。 这种情况发生在肥大/衰竭的心脏中，其中K通道功能的改变有助于复极的分散，从而为折返性心律失常奠定基础。 为了设计针对这些病理状况的有效疗法，重要的是在分子水平上知道是什么导致了K通道分布的这种正常模式以及它在患病心脏中是如何被扰乱的。 本研究的重点是瞬时外向钾电流（Ito）、慢延迟整流钾电流（IKs）和快速延迟整流钾电流（IKr），这是心肌细胞中三种主要的复极化钾电流。 我们将使用狗作为我们的动物模型，并比较正常心脏和慢性心肌梗死心脏中的K通道功能，其中发生了各种重构过程。 我们将应用电生理学、分子生物学、免疫印迹和免疫细胞化学技术来检测通道功能和亚基表达。 该策略是使用在心肌细胞中的天然通道的实验和在体外系统中表达的通道克隆的实验之间的迭代过程，以建立亚基组成和通道功能之间的相关性。 提出了四个具体目标。 在前三个目标下，我们将研究为什么正常心脏中Ito，IKs和IKr的电流密度和门控动力学分别是不均匀的。 这些信息，以及工具（K通道亚基cDNA和抗体），我们在这些目标开发，将应用于目标4下，以检查梗死后心脏K通道重塑的分子基础。 这些实验的结果将为心脏K通道的分子生理学和病理学提供新的见解，这将有助于设计梗死后重塑心脏心律失常的治疗干预措施。