Sex Hormones and Cardiac Arrhythmia in Transgenic LQT2 Rabbits

转基因 LQT2 兔的性激素和心律失常

• 批准号: 8055499
• 负责人: GIDEON KOREN
• 金额: $ 58.73万
• 依托单位: RHODE ISLAND HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8055499
• 关键词: Action Potentials; Adrenergic Receptor; American; Arrhythmia; Biological Models; Calcium; Cardiac; Cardiomyopathies; Cell model; Code; Computer Simulation; Data; Disease; Electrocardiogram; Electrophysiology (science); Engineering; Environmental Risk Factor; Estrogens; Female; Fiber; Gender; Gene Expression; Genes; Genetic; Genetic Models; Genetic Predisposition to Disease; Goals; Gonadal Steroid Hormones; Health; Health Benefit; Heart; Heart Diseases; Heart failure; Heterogeneity; Hormones; Human; In Vitro; Incidence; Investigation; Ion Channel; Knowledge; Lead; Left ventricular structure; Life; Light; Long QT Syndrome; Maps; Mechanics; Mediating; Modeling; Molecular; Molecular Models; Monitor; Muscle Cells; Mutation; Optics; Oryctolagus cuniculus; Pathogenesis; Patients; Pharmaceutical Preparations; Play; Population; Postpartum Period; Potassium; Preparation; Prevention strategy; Progesterone; Property; Proteins; Public Health; Refractory; Right ventricular structure; Risk; Role; Sex Characteristics; Sexual Maturation; Simulate; Stress; Substrate Interaction; Sudden Death; Surface; Sympathetic Nervous System; Syndrome; Tachyarrhythmias; Techniques; Theoretical model; Time; Tissue Model; Tissues; Transgenic Organisms; Ventricular; Withdrawal; base; comparative; drug market; high risk; in vivo; indexing; innovative technologies; insight; loss of function; mRNA Expression; molecular modeling; mutant; novel; novel strategies; patch clamp; prepuberty; protective effect; protein expression; public health relevance; receptor; sudden cardiac death

DESCRIPTION (provided by applicant): Sudden cardiac death (SCD) claims the lives of approximately 350,000 Americans each year. Emerging evidence indicates an important role for genetic predisposition to SCD; however, the molecular determinants have remained elusive. The overall goal of this proposal is to investigate new mechanisms that underlie SCD through the application of innovative technology and the novel use of new genetic models of long QT syndrome 2 (LQT2). This multi-pronged approach includes the investigation of hormone-treated prepubertal, ovariectomized LQT2 rabbits to explore new mechanistic paradigms that underlie the effects of sex hormones on cardiac arrhythmias using in vitro and in silico experimental approaches that will integrate novel molecular, cellular, tissue, and theoretical models. Because gender and the sympathetic nervous system plays a key role in triggering SCD in LQT2, the influence of sex hormones and the autonomic factors on SCD risk will be studied in detail. The proposal is composed of Four Specific Aims: Aim 1: To characterize of the sex hormone induced changes in cardiac repolarization (QT duration and cardiac refractory periods), incidence of spontaneous TdP and sudden cardiac death with the use of telemetric ECG monitoring and in vivo invasive electrophysiological studies; Aim 2: To analyze the action potential duration, dispersion of repolarization, conduction, triggered activity and the heterogeneities in electrical/mechanical restitution, and conduction block using optical mapping of action potential and calcium transients. Aim 3: To define (based on the optical studies) the molecular determinants of the gender differences in cardiac repolarization and excitation by analyzing the gender or sex hormone related differences in the expression of genes coding for the or subunits of the repolarizing potassium currents, calcium currents, and proteins that control Ca++ cycling, and the adrenergic receptors with the use of protein expression studies and quantitative real-time PCR, and cellular electrophysiological studies; and Aim 4: To perform a comparative analysis of action potential and calcium-handling properties in myocytes isolated from hormone-treated LQT2 rabbits under control conditions and during autonomic receptor stimulation, using patch-clamp and fluorescent-indicator techniques. b) To use computer modeling to examine how experimentally defined cellular/molecular alterations in these LQT2 models influence afterdepolarizations and arrhythmogenic substrate formation in simulated cardiac tissue. These studies will contribute to the understanding of the mechanisms that trigger and maintain arrhythmias in hormone-treated rabbits, and therefore lead to a better understanding of gender-related arrhythmias in long QT syndrome. PUBLIC HEALTH RELEVANCE: The characterization of transgenic rabbit models for cardiac arrhythmias, the effects of sex hormones, and the identification of the relationship between mutant LQTS genes that encode for dysfunctional ion channels and life-threatening ventricular tachyarrhythmias should provide more complete knowledge into the genetic and electrophysiologic factors involved in repolarization disorders. These studies into altered ventricular repolarization should contribute important new insights into sudden cardiac death mechanisms associated with acquired cardiac disorders that accompany ischemic and nonischemic cardiomyopathy and QT-prolonging drugs. This enhanced knowledge should lead to more effective strategies for prevention of sudden death in a broad spectrum of genetic and acquired cardiac disorders with meaningful public health benefits.

描述（由申请人提供）：每年约有 350,000 名美国人死于心源性猝死 (SCD)。新出现的证据表明遗传易感性对 SCD 具有重要作用；然而，分子决定因素仍然难以捉摸。该提案的总体目标是通过应用创新技术和长 QT 综合征 2 (LQT2) 的新遗传模型的新用途来研究 SCD 的新机制。这种多管齐下的方法包括研究激素治疗的青春期前、卵巢切除的 LQT2 兔子，以探索性激素对心律失常影响的新机制范式，使用体外和计算机实验方法，整合新的分子、细胞、组织和理论模型。由于性别和交感神经系统在LQT2中触发SCD中起着关键作用，因此将详细研究性激素和自主神经因素对SCD风险的影响。该提案由四个具体目标组成： 目标 1：通过使用遥测心电图监测和体内侵入性电生理学研究来表征性激素引起的心脏复极（QT 持续时间和心脏不应期）变化、自发性 TdP 和心源性猝死的发生率；目标 2：使用动作电位和钙瞬变的光学映射来分析动作电位持续时间、复极化离散度、传导、触发活动以及电/机械恢复的异质性和传导阻滞。目标 3：通过使用蛋白质表达研究和实时定量分析编码复极钾电流、钙电流和控制 Ca++ 循环的蛋白质和肾上腺素能受体的基因或亚基表达的性别或性激素相关差异，定义（基于光学研究）心脏复极和兴奋中性别差异的分子决定因素 PCR 和细胞电生理学研究；目标 4：使用膜片钳和荧光指示剂技术，在对照条件下和自主神经受体刺激期间，对从激素处理的 LQT2 兔子中分离出的肌细胞的动作电位和钙处理特性进行比较分析。 b) 使用计算机模型来检查这些 LQT2 模型中实验定义的细胞/分子改变如何影响模拟心脏组织中的后除极和致心律失常底物形成。这些研究将有助于了解激素治疗兔子引发和维持心律失常的机制，从而更好地了解长 QT 综合征中与性别相关的心律失常。公共健康相关性：转基因兔心律失常模型的特征、性激素的影响以及编码功能失调的离子通道的突变LQTS基因与危及生命的室性快速性心律失常之间关系的鉴定应该为涉及复极障碍的遗传和电生理因素提供更完整的知识。这些关于心室复极改变的研究应该为与缺血性和非缺血性心肌病以及 QT 延长药物相关的获得性心脏疾病相关的心源性猝死机制提供重要的新见解。这种知识的增强应该会带来更有效的策略来预防广泛的遗传性和获得性心脏病中的猝死，并具有有意义的公共健康益处。