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

• 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
• 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

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，它磷酸化L型Ca2+ 渠道和磷兰班，以及其他底物，以增加Ca2+进入和SR Ca2+摄取。这个β- 肾上腺素引起的细胞内Ca2+（Ca2+过载）的增加是一种自然而有效的机制 提高心脏性能，因为心脏收缩的大小和力在很大程度上取决于 Ca2+提供给肌膜的量。但是，CA2+过载也增加了心律不齐的脆弱性 因为它会使ryanodine受体（RYR2）更接近赞助Ca2+释放（SCR）的阈值。 scr 在舒张期间，激活肌膜的Na+/Ca2+交换器，并产生向内的转向电流 （延迟脱皮后或爸爸）可能会触发扩展动作电位。 CA2+超载及其 随后的SCR确实是在恶性心律不齐中演变的主要事件，如在 儿茶酚胺能多态性心室心动过速（CPVT），在某些形式的房间 纤颤，长QT和心力衰竭。为了防止这些Ca2+依赖性心律不齐，RYR2的新兴组 阻止者旨在停止SCR，目的地，目的地是催生SCR的关键过程，即Ca2+超载，可能 RYR2阻滞剂不会受到影响，或者在某些情况下甚至可能会加剧。我们发现 Imperacalcin，一种高亲和力，膜渗透的选择性激动剂，矛盾地降低 心律不齐并防止CPVT动物模型中Ca2+依赖性心律失常。我们假设这一点 Imperacalcin的这种出乎意料且显着的抗心律失常作用是由于部分而受控的 SR Ca2+负载的耗竭，这减少了SCR事件的承诺，从而消散了主 CPVT中的心律失常底物。我们的研究计划将系统，严格地测试 使用已建立的（小鼠）和新型的分子，细胞，全心和完整动物水平的假设 （兔）CPVT的模型。第一个特定目的将确定定义的结构和功能特征 该会议向Imperacalcin和Calcin家族的其他成员进行了会议，他们渗透成会员资格和 他们的抗心律失常特性。在第二个目标中，我们将在完整 心肌细胞，Langendorff丰盛的工作心脏和完整的动物，用于合理化的新颖设计 RYR2配体能够防止Ca2+触发心律不齐。这些研究使用动物模型 CPVT开发一种新型范式，用于治疗Ca2+过载产生的心律不齐；结果 可能需要应用于其他心肌病，其中可能需要控制SR Ca2+的卸载。