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 在心肌细胞激发偶联（ECC）和CA从肌浆网（SR）中释放 具有由于缺乏或不规则组织的横向小管膜而产生的独特特征 系统。心肌细胞具有两种类型的SR，连接（J-SR）和非界面（NJ-SR）。 CA从J-释放 SR通过电压门控L型CA通道的CA进入控制，而NJ-SR的释放则由 随后传播CA诱导的CA释放（CICR）。在心房ECC中，基本问题仍然存在 未解决的：心脏瑞氨烷受体（RYR）SR CA释放通道具有固有的低胞质CA- 敏感性导致难题如何甚至可以激活NJ-SR的CICR。这项调查旨在 建立一个新型的房屋ECC综合模型。心力衰竭（HF）心脏经历结构和 旨在维持足够心脏输出的功能变化（心脏重塑）。我们 将研究HF发展过程中不同阶段的不同阶段，对心房的重塑会导致深刻 心房CA信号，ECC和肌肉的变化有助于维持心脏输出。 特定目的1。确定心房肌细胞中CA释放的独特特性，以确保稳健 CICR。我们将检验一个新的假设“消防 - 散发摄取火”（FDUF）范式用于房间CA和 ECC。通过这种机制，胞质和腔内CA的RYR调节协调作用（串联RYR 激活）在单个SR CA释放单元以及整个SR网络的级别上，CA吸收 Sarco/内质网Ca ATPase和SR内CA扩散可确保鲁棒和有效的CICR。 特定目标2：确定HF进展过程中ECC和CA释放的房屋重塑如何 优化心脏输出。我们将检验以下假设，即在HF的不同阶段，特定于阶段的房屋 重塑通过改变调节心房SR CA释放的分子机制来决定心脏输出， ECC和收缩力。提出的研究将涉及分子，细胞，完整器官和整个体内 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 显微镜检查，细胞缩短测量，全细胞电压和电流夹具技术，单一RYR 通道记录，笼中化合物的亚细胞光解，腺病毒基因转移， 免疫组织化学和生物化学技术。实验工作与计算平行 CA释放和ECC的建模。中心角色扮演兔子慢性HF模型，该模型概括了 人类HF的进展。兔子实验将与对转基因动物的研究相辅相成 CA处理蛋白质的表达水平的特异性改变对CICR和ECC至关重要。细胞研究 将与动物的完整心脏血液动力学研究和体内超声心动图研究相似 在HF进展过程中。