CARDIAC CELL VOLUME REGULATION IN CARDIOPLEGIA

心麻痹中的心肌细胞体积调节

• 批准号: 3365907
• 负责人: CLIVE M BAUMGARTEN
• 金额: $ 21.18万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-08-16 至 1995-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3365907
• 关键词: atrial natriuretic peptide; cell morphology; cell osmotic pressure; heart arrest; heart cell; heart surgery; induced hypothermia; ion transport; laboratory rabbit; microelectrodes; myocardial infarction; single cell analysis; sodium potassium exchanging ATPase

Cellular edema is a critical aspect of myocardial injury. Defects in cell volume regulation are associated with cell damage and contractile and electrical dysfunction during cardioplegia (elective cardiac arrest), ischemia and reflow. Despite its importance, volume regulation by cardiac cells is not well understood. This presents an acute problem for cardioplegia because the solution perfusing the heart must be designed provide myocardial protection during arrest. The goal of these studies is to understand the mechanisms that regulate cardiac cell volume under cardioplegic and physiologic conditions. Processes underlying cell volume control will be identified from measurements of cell volume and determinants of the intracellular ion activities of K+, Na+, Cl- and H+ with ion-selective microelectrodes (ISE) in both isolated ventricular myocytes and papillary muscles from adult and neonatal rabbit hearts. Measurements of cell volume will be made with three independent methods: (1) video microscopy will 'optically section' myocytes; (2) volume will be determined from the resistance to current flow around a single myocyte held in a specially designed pipette; and (3) changes in cytoplasmic compartment volume will be determined by loading papillary muscles or myocytes with tetramethylammonium (TMA+) and measuring the trapped TMA+ with an ISE. We will: (1) Test the hypothesis that isosmotic cardioplegic solutions are anisotonic and cause cell volume to change. (2) Evaluate the role of Na+/K+/2Cl- cotransport, Na+/Cl- cotransport, Na+-K+ pump, Na+-H+ exchange, Cl--HCO3- exchange, and Na+-Ca2+ exchange in the maintenance of cell volume under physiologic and cardioplegic conditions and during osmotic stress. Transport processes will be identified from the effects of transport inhibitors and selective omission of transported ions from the bathing media on both cell volume and intracellular ion activities. (3) Assess the role of mobile anions and the [K+] [Cl-] product in setting cell volume. (3) Test the hypothesis that cell volume control is different in neonatal and adult cells. (4) Determine the effect of altering pHi and metabolic inhibition on cell volume. (5) In a working heart model, compare the efficacy of standard cardioplegic solutions to that of 'improved' solutions designed to better regulate cell volume. The combination of intracellular ion activity measurements with novel techniques for determining cell volume in isolated myocytes and papillary muscles can provide unique information about the response of cardiac cells to perturbations that alter cell volume and allow identification of solute transport pathways that contribute to regulation of cell volume and, ultimately, to the integrity of the cell membrane. The significance of these experiments is that they will provide insight into a basic, critical, physiological processes that are virtually unexplored in heart. Knowledge of the factors responsible for cell volume control is a necessary prerequisite for understanding pathophysiological disturbances of cell volume, such as those occurring during cardioplegia and infarction.

细胞水肿是心肌损伤的一个重要方面。电池中的缺陷 容量调节与细胞损伤和收缩有关， 心脏停搏期间的电功能障碍(选择性心脏骤停)， 缺血和复流。尽管它很重要，但心脏的容量调节 对细胞的了解还不是很清楚。这提出了一个尖锐的问题 心脏停搏，因为心脏灌流的溶液必须设计 在心脏骤停时提供心肌保护。 这些研究的目标是了解调控机制 心脏停搏和生理状态下的心肌细胞体积。 单元格体积控制的基础流程将从 细胞体积和细胞内离子决定因素的测量 离子选择微电极对K~+、Na~+、Cl~-和H~+的活度 在分离的心肌细胞和乳头肌中， 新生的兔心。细胞体积的测量将用 三种独立的方法：(1)视频显微镜将进行光学切片 肌细胞；(2)体积由电流阻力决定。 在特殊设计的吸管中保持单个心肌细胞的周围；以及(3) 细胞质隔室体积的变化将由负荷决定 乳头状肌或肌细胞四甲基铵(TMA+)染色及测定 使用ISE捕获的TMA+。 我们将：(1)检验等渗停搏液是 各向同性并引起细胞体积改变。(二)评估企业的作用 Na+/K+/2Cl-共转运，Na+/Cl-共转运，Na+-K+泵，Na+-H+交换， CL--HCO3-交换和Na+-Ca~(2+)交换在维持细胞体积中的作用 在生理和心脏停搏状态下以及在渗透应激状态下。 运输过程将从运输的影响中确定 缓蚀剂与浴液中迁移离子的选择性去除 培养液对细胞体积和细胞内离子活性的影响。(3)评估 流动阴离子和[K+][Cl-]产物在设定细胞体积中的作用。 (3)检验新生儿细胞体积控制不同的假设 和成体细胞。(4)确定改变phi和代谢的效果 抑制细胞体积。(5)在工作心脏模型中，比较 标准停搏液对“改良”停搏液的疗效 旨在更好地调节细胞体积。 细胞内离子活度测量与新技术的结合 测定分离的心肌细胞和乳头状肌细胞体积的技术 肌肉可以提供有关心肌细胞反应的独特信息。 对改变晶胞体积并允许识别溶质的扰动 有助于调节细胞体积的运输途径， 最终，对细胞膜的完整性。的重要意义。 这些实验将提供对一个基本的、关键的、 在心脏中几乎没有被探索过的生理过程。知识 在负责细胞体积控制的因素中是必要的 了解细胞病理生理障碍的前提条件 容量，如在心脏停搏和脑梗塞期间发生的。