Partial and Controlled Depletion of SR Calcium by RyR Agonists Prevents Calcium-dependent Arrhythmias

RyR 激动剂部分且受控地消耗 SR 钙可预防钙依赖性心律失常

基本信息

批准号：
10577630
负责人：
Francisco J Alvarado
金额：
$ 61.68万
依托单位：
UNIVERSITY OF WISCONSIN-MADISON
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-01-01 至 2026-12-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10577630
关键词：
Action Potentials Adrenergic Agents Adrenergic beta-Antagonists Affect Affinity Agonist Animal Model Animals Anti-Arrhythmia Agents Arrhythmia Arrhythmogenic Right Ventricular Dysplasia Atrial Fibrillation Binding Biological Assay Buffers Calcium Calsequestrin Cardiac Cardiac Myocytes Cardiomyopathies Catecholaminergic Polymorphic Ventricular Tachycardia Cell Membrane Permeability Cell physiology Cells Cellular Membrane Characteristics Child Cyclic AMP-Dependent Protein Kinases Development Diastole Disease Environment Event Family Functional disorder Genes Heart Heart failure Hyperactivity Individual Knock-in Ligands Malignant - descriptor Mediating Membrane Metabolic Microfilaments Modeling Molecular Mus Muscle Cells Mutation Oryctolagus cuniculus Output Pathologic Penetration Peptides Performance Perfusion Phosphorylation Play Process Property Proteins Rationalization Receptor Gene Research Role RyR2 Ryanodine Receptor Calcium Release Channel Sarcolemma Sarcoplasmic Reticulum Scorpion Venoms Signal Transduction Strenuous Exercise Stress Syndrome Testing Ventricular Ventricular Fibrillation Ventricular Tachycardia autosome design insight member novel phospholamban prevent programs stem uptake young adult

项目摘要

ABSTRACT Sympathetic stimulation of ventricular myocytes activates PKA, which phosphorylates L-type Ca2+ channels and phospholamban, among other substrates, to increase Ca2+ entry and SR Ca2+ uptake. This β- adrenergic-induced increase of intracellular Ca2+ (Ca2+ overload) is a natural and efficient mechanism to increase cardiac performance, inasmuch as the magnitude and force of cardiac contractions greatly depend on the amount of Ca2+ supplied to the myofilaments. However, Ca2+ overload also increases arrhythmia vulnerability because it brings ryanodine receptors (RyR2) closer to threshold for spontaneous Ca2+ release (SCR). SCR during diastole activates the Na+/Ca2+ exchanger of the sarcolemma and generates a depolarizing inward current (delayed after-depolarization or DAD) that may trigger extemporaneous actions potentials. Ca2+ overload and its subsequent SCRs are indeed the primary events that evolve in malignant cardiac arrhythmias, as observed in Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) and quite possibly in some forms of atrial fibrillation, long QT, and heart failure. To prevent these Ca2+-dependent arrhythmias, an emergent group of RyR2 blockers aim to stop SCR, despite the fact that the key process that spawns SCR, namely, Ca2+ overload, may not be affected or in some cases may be even exacerbated by the RyR2 blockers. We have found that imperacalcin, a high-affinity, membrane-permeable selective agonist of RyRs, paradoxically decreases arrhythmia burden and prevents Ca2+-dependent arrhythmias in animal models of CPVT. We hypothesize that this unexpected and remarkable anti-arrhythmic effect of imperacalcin is due to a partial and controlled depletion of SR Ca2+ load, which decreases the propensity of SCR events and thus dissipates the main arrhythmogenic substrate in CPVT. Our research program will systematically and rigorously test this hypothesis at the molecular, cellular, whole heart and intact animal levels using established (mouse) and novel (rabbit) models of CPVT. The first specific aim will determine the defining structural and functional characteristics that confer to imperacalcin and other members of the calcin family their capacity to permeate membranes and their anti-arrhythmic properties. In the second aim, we will use native and modified calcins on intact cardiomyocytes, Langendorff-perfused working hearts and intact animals for a rationalized design of a novel group of RyR2 ligands capable of preventing Ca2+-triggered arrhythmias. These studies use animal models of CPVT to develop a novel paradigm for the treatment of Ca2+ overload-generated cardiac arrhythmias; results may be applied to other cardiomyopathies where controlled unloading of SR Ca2+ may be desirable.

抽象的心室肌细胞的交感神经刺激激活 PKA，磷酸化 L 型 Ca2+ 通道和受磷蛋白等底物，以增加 Ca2+ 进入和 SR Ca2+ 摄取。肾上腺素诱导的细胞内 Ca2+ 增加（Ca2+ 过载）是一种自然而有效的机制提高心脏功能，因为心脏收缩的幅度和力量很大程度上取决于然而，Ca2+ 超负荷也会增加心律失常的风险。因为它使兰尼碱受体 (RyR2) 更接近自发 Ca2+ 释放 (SCR) 的阈值。舒张期激活肌膜的 Na+/Ca2+ 交换器并产生去极化内向电流（延迟后除极或 DAD）可能会引发临时动作电位及其 Ca2+ 过载。随后的 SCR 确实是恶性心律失常中演变的主要事件，正如在儿茶酚胺能多形性室性心动过速 (CPVT)，很可能出现在某些形式的心房心动过速中为了预防这些 Ca2+ 依赖性心律失常，出现了一组 RyR2。阻滞剂旨在阻止 SCR，尽管事实上产生 SCR 的关键过程（即 Ca2+ 超载）可能会我们发现，RyR2 阻滞剂不受影响，甚至在某些情况下可能会加剧。 imperacalcin 是一种高亲和力、膜渗透性的 RyRs 选择性激动剂，相反，它会降低在 CPVT 动物模型中减轻心律失常负担并预防 Ca2+ 依赖性心律失常。英普拉钙素这种意想不到的、显着的抗心律失常作用是由于部分和受控的 SR Ca2+ 负载耗尽，这降低了 SCR 事件的倾向，从而消散了主要我们的研究计划将系统、严格地测试这一点。使用已建立的（小鼠）和新颖的分子、细胞、整个心脏和完整动物水平的假设 CPVT（兔）模型的第一个具体目标将确定定义的结构和功能特征。赋予英普拉钙素和钙素家族其他成员渗透膜的能力它们的抗心律失常特性在第二个目标中，我们将在完整的钙素上使用天然和修饰的钙素。心肌细胞、Langendorff 灌注的工作心脏和完整的动物，以合理地设计新颖的这些研究使用了能够预防 Ca2+ 引发的心律失常的 RyR2 配体组。 CPVT 开发了治疗 Ca2+ 超载引起的心律失常的新范例；可应用于可能需要控制 SR Ca2+ 卸载的其他心肌病。