E-C Coupling and Ca2+ Regulation atrial myocytes

E-C 耦合和 Ca2 调节心房肌细胞

• 批准号: 7561381
• 负责人: LOTHAR A BLATTER
• 金额: $ 21.66万
• 依托单位: RUSH UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7561381
• 关键词: 3-Dimensional; Adenylate Cyclase; Adrenergic Agents; Adrenergic Receptor; Affect; Arachidonic Acids; Arrhythmia; Autonomic nervous system; Behavior; Cardiac; Cardiovascular system; Cells; Characteristics; Condition; Coupled; Coupling; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Endothelin-1; Event; Frequencies; GTP-Binding Proteins; Generations; Goals; Heart Atrium; Image; Imaging Techniques; Inositol Phosphates; Laser Scanning Confocal Microscopy; Lead; Lipid Bilayers; Measurement; Mechanics; Mediating; Membrane; Methods; Morbidity - disease rate; Muscle; Muscle Cells; Nitric Oxide; Nitric Oxide Signaling Pathway; Nitric Oxide Synthase; Pattern; Phospholipases A; Play; Predisposition; Production; Protein Kinase; Pump; Receptor Signaling; Regulation; Research; Resolution; Role; Sarcoplasmic Reticulum; Signal Pathway; Signal Transduction; Site; Techniques; Testing; Tissues; Ventricular; Vesicle; Voltage-Clamp Technics; adrenergic; analog; beta-adrenergic receptor; inositol 1-phosphate; mortality; photolysis; prevent; receptor; reconstitution; spatial relationship; tool; uptake

DESCRIPTION (provided by applicant): During excitation-contraction (e-c) coupling Ca2+ release from the sarcoplasmic reticulum (SR) in atrial myocytes differs significantly from ventricular myocytes. Atrial myocytes lack transverse tubules and have two different types of SR, junctional (j-SR) and non-junctional SR (nj-SR). Ca2+ release during e-c coupling is spatially inhomogeneous. Ca2+-induced Ca2+-release (CICR) from j-SR and nj-SR is regulated by distinctly different mechanisms. In atrial myocytes IP3-dependent Ca2+ signalling modulates Ca2+ signaling during e-c coupling and cardiac contractility is regulated by the autonomic nervous system. Beta-adrenergic receptor (betaa-AR) signaling mediates symapathetic regulation of cardiac function through intracellular signaling pathways involving G-proteins, protein kinases, nitric oxide (NO) and Ca2+. Ca2+ alternans reflects the alternations of the Ca2+ transient amplitude at regular pacing frequency which results in electromechanical alternans. Atrial Ca2+ alternans are directly related to the generation of atrial arrhythmias which is a major contributor to cardiovascular morbidity and mortality. The overall goal of the proposed study is to elucidate mechanisms and signalling pathways that are relevant to normal atrial e-c coupling and their perturbations which lead to Ca2+ alternans and therefore arrhythmogenic behavior in atrial tissue. The following Specific Aims are proposed: Specific Aim #1: Determine the subcellular mechanisms by which inositol-phosphate (IP3) signaling governs Ca2+ signaling during e-c coupling. Specific Aim #2. Determine the mechanisms by which a-adrenergic signaling regulates Ca2+ release from j-SR and nj-SR during e-c coupling. Specific Aim #3. Elucidate the mechanisms through which disturbance(s) of IP3-, a-AR- and NO-dependent signaling leads to Ca2+ aiternans. To achieve these aims a multitude of experimental techniques will be used: high resolution [Ca2+]i imaging by laser scanning confocal microscopy in single atrial myocytes, whole-cell voltage clamp techniques to study membrane currents, single channel recordings through cardiac SR Ca2+ release channels reconstituted into planar lipid bilayers, subcellular photolysisof caged Ca2+ and IP3, and pharmacological manipulation of a-adrenergic regulation, IP3 signaling and Ca2+ entry, release and uptake. The proposed research will provide fundamental new information on the regulation of atrial e-c coupling and Ca2+ release under normal and altered conditions relevant to atrial arrhythmias.

描述（由申请人提供）：在兴奋-收缩（e-c）耦合过程中，心房肌细胞肌浆网（SR）释放的 Ca2+ 与心室肌细胞显着不同。心房肌细胞缺乏横管，并具有两种不同类型的 SR：交界型 (j-SR) 和非交界型 SR (nj-SR)。 e-c 耦合过程中 Ca2+ 的释放在空间上不均匀。 j-SR 和 nj-SR 中 Ca2+ 诱导的 Ca2+ 释放 (CICR) 受到明显不同的机制调节。在心房肌细胞中，IP3 依赖性 Ca2+ 信号在 e-c 耦合过程中调节 Ca2+ 信号，并且心肌收缩力由自主神经系统调节。 β-肾上腺素能受体 (beta-AR) 信号通过涉及 G 蛋白、蛋白激酶、一氧化氮 (NO) 和 Ca2+ 的细胞内信号传导途径介导心脏功能的交感神经调节。 Ca2+ 交替反映了 Ca2+ 瞬态幅度在规则起搏频率下的交替，从而导致机电交替。心房 Ca2+ 交替与房性心律失常的产生直接相关，房性心律失常是心血管疾病发病率和死亡率的主要原因。本研究的总体目标是阐明与正常心房 e-c 耦合及其扰动相关的机制和信号通路，这些扰动导致 Ca2+ 交替，从而导致心房组织中的致心律失常行为。提出以下具体目标： 具体目标#1：确定肌醇磷酸 (IP3) 信号传导在 e-c 耦合过程中控制 Ca2+ 信号传导的亚细胞机制。 具体目标#2。确定在 e-c 耦合过程中 a-肾上腺素信号传导调节 j-SR 和 nj-SR 中 Ca2+ 释放的机制。 具体目标#3。阐明 IP3-、a-AR- 和 NO 依赖性信号传导紊乱导致 Ca2+ 备用的机制。 为了实现这些目标，将使用多种实验技术：通过激光扫描共聚焦显微镜对单个心房肌细胞进行高分辨率 [Ca2+]i 成像、研究膜电流的全细胞电压钳技术、通过心脏 SR Ca2+ 释放通道进行单通道记录重组为平面脂质双层，笼中 Ca2+ 和 IP3 的亚细胞光解，以及 α-肾上腺素能调节、IP3 信号传导和 Ca2+ 进入、释放和摄取的药理学操作。 拟议的研究将为房性心律失常相关的正常和改变条件下心房 e-c 耦合和 Ca2+ 释放的调节提供基本的新信息。