Cardiomyocyte stretch and intracellular calcium release with advancing age

随着年龄的增长，心肌细胞伸展和细胞内钙释放

• 批准号: 8383278
• 负责人: Timothy Lee Domeier
• 金额: $ 11.3万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8383278
• 关键词: Abbreviations; Affect; Age; Aging; American; Americas; Arrhythmia; Award; Blood; C57BL/6 Mouse; Calcium; Calcium Oscillations; Cardiac; Cardiac Myocytes; Cells; Confocal Microscopy; Contractile Proteins; Coupling; Dantrolene; Data; Development; Diastole; Elderly; Elements; Environment; Event; Exhibits; Fluo 4; Functional disorder; Gerontology; Goals; Heart; Heart Diseases; Image; In Situ; Individual; Lead; Left; Length; Measurement; Measures; Mechanics; Mentors; Methods; Missouri; Mus; Muscle Cells; Myocardium; Organ; Physiologic intraventricular pressure; Physiology; Population; Property; Public Health; Pump; Regulation; Relaxation; Research; Research Personnel; Research Project Grants; Research Proposals; Resolution; Ryanodine Receptor Calcium Release Channel; Sarcomeres; Sarcoplasmic Reticulum; Stretching; Systole; Techniques; Testing; Time; Training; Translating; Universities; Ventricular; Work; aged; aging population; calcium indicator; career; experience; falls; human old age (65+); improved; inhibitor/antagonist; innovation; insight; middle age; novel; novel therapeutics; pressure; prevent; response; senescence; skills; therapy development

DESCRIPTION (provided by applicant): Nearly 1 in 8 (12.5%) of Americans are older than 65 years and the number of individuals 65 and over is expected to increase to ~20% over the next 2 decades. Cardiac disease is prevalent in the aged population and therefore represents a major public health concern in America. The heart remodels with advancing age and these remodeling events often result in the impaired ability of the heart to relax between each beat. This period of relaxation is the cardiac diastole, during which time the heart fills with blood and prepares for the next contraction during systole. With aging, diastolic dysfunction is characterized by increased "stiffness". Given that greater stiffness makes it harder to fill, the heart is less effective as a pump and operates at elevated filling pressures and volumes with a greater propensity for arrhythmia. Because the mechanism(s) underlying cardiac dysfunction with advancing age are poorly understood, developing new therapeutic treatments for affected individuals requires new mechanistic insight. The rise and fall of calcium concentration within cardiac cells controls their contraction and relaxation, respectively, and is regulated by the sarcoplasmic reticulum ("SR"). Therefore, this project is focused on understanding how aging alters the relationship between diastolic filling (i.e., passive stretching of cardiac myocytes) an calcium release from the SR. To directly observe well-defined functional elements (e.g., calcium "sparks" and "waves") of calcium release, high resolution confocal imaging will be used with fluorescent calcium indicators (Fluo-4) with reference to the well-defined spacing of contractile proteins (i.e., sarcomere length). More specifically, this research project will compare intact perfused hearts and enzymatically dissociated intact ventricular cardiomyocytes from young (3 month), middle-aged (14 month), and senescent (24 month) C57BL/6 mice to test the central hypothesis that with advancing age cardiomyocytes have increased passive stiffness with highly sensitive coupling between stretch and SR calcium release. Aim 1 will determine the actual changes that occur in cell and sarcomere lengths of young, middle-aged, and senescent hearts in response to defined changes in left ventricular filling pressure. In Aim 2, the length of individual isolated cardiomyocytes will be controlled to determine how passive stretch of the cell alters calcium release in order to identify key age-associated differences in cell stiffness and calcium regulation. In Aim 3, findings from Aims 1 and 2 will be integrated by investigating calcium release and pressure development within the intact, working heart. Overall, this project utilizes innovative methods to study the function of individual cardiomyocytes under highly controlled experimental conditions as well as in their native environment within the intact heart. This mentored award will also provide important technical training in a highly integrative environment at the University of Missouri, which will give the applicant unique experimental skills and valuable perspective into cardiac physiology as it relates to aging populations. It is anticipated that results from this project will yield insight into the mechanisms of cardiac diseas during aging, with the ultimate goal of translating these findings into treatments for the aging population. PUBLIC HEALTH RELEVANCE: The healthy heart exhibits highly coordinated intracellular calcium release in order to function as an effective pump. Alterations in calcium release during diastolic filling (i.e., passive stretch) predispose the heart to impaired filling and arrhythmia, which are commonly associated with aging. This research proposal investigates how aging affects stretch-induced intracellular calcium release with the goal of translating our findings int the development of therapies to improve cardiac function in the aging population.

描述（由申请人提供）：近八分之一 (12.5%) 的美国人年龄超过 65 岁，预计未来 20 年 65 岁及以上的人数将增加到约 20%。心脏病在老年人口中普遍存在，因此是美国主要的公共卫生问题。心脏随着年龄的增长而重塑，这些重塑事件通常会导致心脏每次跳动之间的放松能力受损。这个放松的时期就是心脏舒张期，在此期间心脏充满血液， 为收缩期的下一次收缩做准备。随着年龄的增长，舒张功能障碍的特点是“僵硬”增加。鉴于硬度越大，填充越困难，心脏作为泵的效率较低，并且在升高的填充压力和容量下运行，更容易发生心律失常。由于人们对随着年龄增长导致心脏功能障碍的机制知之甚少，因此为受影响的个体开发新的治疗方法需要新的机制见解。心肌细胞内钙浓度的上升和下降分别控制其收缩和舒张，并受到肌浆网（“SR”）的调节。因此，该项目的重点是了解衰老如何改变舒张期充盈（即心肌细胞的被动拉伸）与 SR 钙释放之间的关系。为了直接观察钙释放的明确功能元素（例如钙“火花”和“波”），高分辨率共聚焦成像将与荧光钙指示剂（Fluo-4）结合使用，参考明确的收缩间距蛋白质（即肌节长度）。更具体地说，该研究项目将比较来自年轻（3 个月）、中年（14 个月）和衰老（24 个月）C57BL/6 小鼠的完整灌注心脏和酶解完整心室心肌细胞，以测试中心假设，即随着进展年龄较大的心肌细胞被动硬度增加，拉伸和SR钙释放之间的耦合高度敏感。目标 1 将确定年轻、中年和衰老心脏的细胞和肌节长度发生的实际变化，以响应左心室充盈压的确定变化。在目标 2 中，将控制单个分离心肌细胞的长度，以确定细胞的被动拉伸如何改变钙释放，从而确定细胞硬度和钙调节方面与年龄相关的关键差异。在目标 3 中，目标 1 和 2 的发现将通过研究完整、工作的心脏内的钙释放和压力发展来整合。总体而言，该项目利用创新方法来研究单个心肌细胞在高度受控的实验条件下以及完整心脏内的原生环境中的功能。该指导奖项还将在密苏里大学高度一体化的环境中提供重要的技术培训，这将为申请人提供独特的实验技能和与人口老龄化相关的心脏生理学的宝贵视角。预计该项目的结果将深入了解衰老过程中心脏病的机制，最终目标是将这些发现转化为针对老龄化人口的治疗方法。 公共健康相关性：健康的心脏表现出高度协调的细胞内钙释放，以发挥有效的泵作用。舒张期充盈期间钙释放的变化（即被动拉伸）使心脏容易出现充盈受损和心律失常，这通常与衰老有关。这项研究计划调查衰老如何影响拉伸诱导的细胞内钙释放，目的是将我们的发现转化为改善老年人心脏功能的疗法的开发。