Pathophysiological Regulation of Atrial Myocyte Excitation-Contraction Coupling and Calcium Signaling

心房肌细胞兴奋-收缩耦合和钙信号传导的病理生理调节

• 批准号: 9924276
• 负责人: LOTHAR A BLATTER
• 金额: $ 38.75万
• 依托单位: RUSH UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9924276
• 关键词: ATP phosphohydrolase; Action Potentials; Affect; Animal Experiments; Animals; Atrial Function; Biochemistry; Buffers; Calcium; Calcium Signaling; Calcium ion; Calsequestrin; Cardiac; Cardiac Output; Cells; Closure by clamp; Complement; Computer Models; Confocal Microscopy; Congestive Heart Failure; Coupling; Diffuse; Diffusion; Echocardiography; Endoplasmic Reticulum; Ensure; Event; Fire - disasters; Gene Transfer; Goals; Heart; Heart Atrium; Heart Diseases; Heart failure; Human; ITPR1 gene; Immunohistochemistry; Individual; Inositol; Investigation; Measurement; Membrane; Microfilaments; Mitochondria; Modeling; Molecular; Muscle Cells; Organ; Oryctolagus cuniculus; Pathologic; Peripheral; Play; Property; Proteins; Pump; Reaction; Receptor Activation; Regulation; Resolution; Risk; Role; Ryanodine Receptor Calcium Release Channel; Sarcoplasmic Reticulum; Signal Transduction; Site; Specific qualifier value; Speed; Structure; System; Techniques; Testing; Therapeutic; Time; Transgenic Animals; Ventricular; Ventricular Remodeling; Work; cardiogenesis; cytosolic receptor; density; experimental study; hemodynamics; in vivo; interest; novel; parallel computer; photolysis; receptor; spatiotemporal; tripolyphosphate; uptake; voltage

PROJECT SUMMARY/ABSTRACT In atrial myocytes excitation-contraction coupling (ECC) and Ca release from the sarcoplasmic reticulum (SR) have unique features that result from the lack or the irregular organization of the transverse tubule membrane system. Atrial myocytes have two types of SR, junctional (j-SR) and non-junctional (nj-SR). Ca release from j- SR is controlled by Ca entry through voltage-gated L-type Ca channels whereas release from nj-SR occurs by subsequent propagating Ca-induced Ca release (CICR). In atrial ECC a fundamental question has remained unanswered: The cardiac ryanodine receptor (RyR) SR Ca release channel has an inherently low cytosolic Ca- sensitivity resulting in a conundrum how CICR from the nj-SR can even be activated. This investigation aims to establish a novel comprehensive model of atrial ECC. In heart failure (HF) the heart undergoes structural and functional changes (cardiac remodeling) that are aimed towards maintaining an adequate cardiac output. We will investigate how at different stages during the development of HF, remodeling of the atria leads to profound changes in atrial Ca signaling, ECC and inotropy that contribute to maintaining cardiac output. Specific aim 1. Determine the unique properties of Ca release in atrial myocytes that ensure robust CICR. We will test a novel hypothesis of a 'fire-diffuse-uptake-fire' (FDUF) paradigm for atrial Ca release and ECC. By this mechanism the coordinated action of RyR regulation by cytosolic and luminal Ca (tandem RyR activation) at the level of individual SR Ca release units as well as the entire SR network, Ca uptake by sarco/endoplasmic reticulum Ca ATPase and intra-SR Ca diffusion assure robust and efficient CICR. Specific aim 2: Determine how atrial remodeling of ECC and Ca release during the progression of HF optimizes cardiac output. We will test the hypothesis that at different stages of HF, stage-specific atrial remodeling determines cardiac output by altering molecular mechanisms that regulate atrial SR Ca release, ECC and contractility. The proposed studies will involve molecular, cellular, intact organ and in-vivo whole animal experiments. We will use a multitude of experimental techniques: high resolution [Ca]i, [Ca]mito and [Ca]SR confocal microscopy, cell shortening measurements, whole-cell voltage and current clamp techniques, single RyR channel recordings, subcellular photolysis of caged compounds, adenoviral gene-transfer, immunohistochemistry and biochemistry techniques. Experimental work is paralleled by computational modeling of Ca release and ECC. A central role plays a rabbit chronic HF model that recapitulates the progression of HF in humans. Rabbit experiments will be complemented with studies on transgenic animals with specific alterations in expression levels of Ca handling proteins crucial to CICR and ECC. Cellular studies will be paralleled with intact heart hemodynamic studies and in-vivo echocardiographic studies in animals during progression of HF.

项目摘要/摘要 心房肌细胞兴奋收缩偶联(ECC)与肌浆网(SR)钙释放 具有独特的特征，这是由于缺乏或不规则的横管膜组织所致 系统。心房肌细胞有交界性(j-SR)和非交界性(Nj-SR)两种类型。CA从j-释放- SR受电压门控L型钙通道的钙内流控制，而NJ-SR的钙释放受 随后传播性钙诱导钙释放(CICR)。在心房ECC中，一个根本性的问题仍然存在 未回答：心脏兰尼定受体(RyR)SR钙释放通道具有固有的低细胞内钙- 敏感性导致了一个难题，即如何激活来自NJ-SR的CICR。这项调查旨在 建立一种新的心房ECC综合模型。在心力衰竭(HF)中，心脏经历结构性和 旨在维持足够的心输出量的功能改变(心脏重塑)。我们 将研究在心力衰竭发展的不同阶段，心房重构如何导致深刻的 有助于维持心输出量的心房钙信号、ECC和肌力的变化。 具体目标1.确定确保强健的心房肌细胞钙释放的独特特性 CICR。我们将测试一种新的假说，即“火-弥散-摄取-火”(FDUF)范式，用于心房钙释放和 ECC。通过这一机制，胞浆和腔内钙调节RyR的协同作用(串联RyR 激活)在单个SR钙释放单元以及整个SR网络的水平上，通过 肌浆网/内质网钙ATPase和肌浆内钙扩散保证了强大和有效的CICR。 特定目标2：确定心力衰竭进展过程中ECC和Ca的心房重构如何释放 优化心输出量。我们将检验这一假设，在心力衰竭的不同阶段，特定阶段的心房 重构通过改变调节心房肌浆网钙释放的分子机制来决定心输出量。 ECC和伸缩性。拟议的研究将涉及分子、细胞、完整器官和体内整体。 动物实验。 我们将使用多种实验技术：高分辨率[Ca]i、[Ca]Mito和[Ca]SR共聚焦 显微镜、细胞缩短测量、全细胞电压和电流钳制技术、单次RyR 通道记录，笼状化合物的亚细胞光解，腺病毒基因转移， 免疫组织化学和生化技术。实验工作与计算工作并行 钙释放和细胞外钙离子浓度的模拟。一个核心角色是兔慢性心力衰竭模型，它概括了 心衰在人类中的进展。兔子实验将与转基因动物的研究相辅相成 钙调节蛋白表达水平的特定变化对CICR和ECC至关重要。细胞研究 将与完整的心脏血流动力学研究和动物体内超声心动图研究平行进行 在心力衰竭进展过程中。