Ionic Homeostasis in Anoxic Cardiac Muscle Cells

缺氧心肌细胞中的离子稳态

• 批准号: 6711158
• 负责人: Robert W Hadley
• 金额: $ 25.76万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-08-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6711158
• 关键词: calcium flux; calcium ion; cardiac myocytes; cell death; confocal scanning microscopy; cytoprotection; diazoxide; free radical oxygen; guinea pigs; ion transport; laboratory rat; membrane transport proteins; myocardial ischemia /hypoxia; potassium channel; reperfusion; sarcolemma; sodium ion; tissue /cell culture

DESCRIPTION (provided by applicant): This project's long-term goal is to define the mechanisms by which altered Ca2+ homeostasis contributes to hypoxic injury in cardiac muscle, and to identify beneficial pharmacological mechanisms that can target these mechanisms. Therefore these studies are aimed at obtaining basic information that will also be relevant to myocardial ischemia/reperfusion. The project will test a new hypothesis focused on the cytoprotective mechanisms of diazoxide, an activator of mitochondrial ATP-dependent K+ channels (KATP). Specifically, it is proposed that diazoxide inhibits the reactivation of the sarcolemmal Na+/Ca2+ exchanger (NCX) during reoxygenation, and that this protects against Ca2+ overload and many types of Ca2+-induced injury in cardiac myocytes. This central hypothesis will be tested through four specific aims. 1) Determine the mechanism by which the reactive oxygen species (ROS) generated during hypoxia/reoxygenation stimulate NCX activity. 2) Determine whether diazoxide inhibits NCX activity during reoxygenation by decreasing the generation of ROS. 3) Determine whether diazoxide exerts its cytoprotective effects during hypoxia by modulating cytosolic and intra-mitochondrial [Ca2+]. 4) Test the hypothesis that diazoxide can selectively inhibit arrhythmogenic transient inward currents when they are induced by Ca2+ overload and NCX activation during hypoxia/reoxygenation. These aims will be investigated in hypoxic guinea-pig and rat cardiac myocytes. Ca2+ homeostasis and NCX activity will be studied using cell imaging, immunocytochemical, and electrophysiological methods. The role of mitochondrial KATP channels will be studied using pharmacological methods and confocal imaging. Two particular strengths of the proposal are that it hypothesizes a novel link between activation of mitochondrial KATP and Ca2+ signaling based on this lab's previous studies, and that our extensive experience studying the NCX should facilitate a definitive test of the hypothesis.

描述（由申请人提供）：该项目的长期目标是定义改变CA2+稳态改变的机制，导致心脏肌肉中缺氧损伤，并确定可以针对这些机制的有益药理机制。因此，这些研究旨在获得与心肌缺血/再灌注有关的基本信息。该项目将检验一个新的假设，该假设的重点是二氮氧化物的细胞保护机理，二氮氧化物是线粒体ATP依赖性K+通道（KATP）的激活剂。具体而言，建议二氮氧化物抑制在氧化过程中肌膜Na+/Ca2+交换器（NCX）的重新激活，这可以预防Ca2+过载和许多类型的CA2+诱导的心肌损伤。 该中心假设将通过四个特定目标进行检验。 1）确定在缺氧/二氧化过程中产生的活性氧（ROS）刺激NCX活性的机制。 2）确定二氮二氧化物是否通过减少ROS的产生来抑制RexygANITION期间的NCX活性。 3）确定二氮氧化物是否通过调节胞质和肌液内[Ca2+]来施加缺氧期间的细胞保护作用。 4）检验二氮氧化物可以选择性地抑制心律失常的瞬态向内电流的假说，当它们在缺氧/re氧中通过Ca2+过载和NCX激活诱导时。 这些目标将在缺氧的几内亚猪和大鼠心肌细胞中进行研究。 CA2+稳态和NCX活性将使用细胞成像，免疫细胞化学和电生理方法研究。线粒体KATP通道的作用将使用药理学方法和共聚焦成像进行研究。该提案的两个特殊优势是，它假设基于该实验室的先前研究，线粒体KATP和Ca2+信号传导之间的激活之间存在新的联系，并且我们研究NCX的丰富经验应促进对假设的确切检验。