L-type Channel Calcium Entry Triggered Diastolic Calcium Sparks

L 型通道钙进入触发舒张期钙火花

• 批准号: 7615779
• 负责人: William Cecil Lester
• 金额: $ 2.92万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7615779
• 关键词: Acute; Address; Adult; Animals; Arrhythmia; Automobile Driving; Biological Models; Buffers; Calcium; Calcium Channel; Cardiac; Cell membrane; Chest; Coupling; Cytosol; Data; Dependence; Diastole; Dimensions; Disease; Electrophysiology (science); Embryo; Excision; Exhibits; Frequencies; Goals; Heart Diseases; Heart failure; Homeostasis; Image; Kinetics; L-Type Calcium Channels; Label; Lead; Location; Membrane Potentials; Modeling; Mus; Muscle Cells; Pathology; Pathway interactions; Phenotype; Physiological; Population; Proteins; Route; RyR2; Ryanodine Receptor Calcium Release Channel; Ryanodine Receptors; Sarcoplasmic Reticulum; Scanning; Series; Sodium-Calcium Exchanger; Source; Time; Ventricular; Ventricular Arrhythmia; Work; base; design; extracellular; mature animal; release of sequestered calcium ion into cytoplasm; sudden cardiac death; voltage

DESCRIPTION (provided by applicant): Dysregulation of calcium in the cardiac ventricular myocyte is prevalent in many pathological models of heart disease such as heart failure and sudden cardiac death. Over the steady state, plasma membrane (PM) calcium entry must equal plasma membrane calcium extrusion to maintain calcium homeostasis. The major PM entry pathway is the L-type Ca channel, and the major PM extrusion pathway is the Na-Ca exchanger (NCX). Calcium may enter the cytosol during diastole via PM leak, and via unitary releases of calcium from intracellular stores - labeled as calcium sparks. Sodium-Calcium exchanger extrusion of calcium during diastole contributes a depolarization of membrane potential. Thus, diastolic calcium fluxes, via forward mode NCX can trigger ventricular cardiac arrhythmias, and can contribute to sudden cardiac death. Diastolic sparks are well-characterized in terms of dimension and location, yet the mechanism of how they are triggered remains a mystery. However, my pilot data suggests that calcium entry through the L-type calcium channel is a required input for a diastolic spark to occur in developing mouse ventricular myocyte. Therefore, the overall purpose of this proposal is to determine the trigger and the source of diastolic calcium sparks. My preliminary data leads me to the overall driving hypothesis: the L-type calcium channel entry triggers diastolic calcium sparks. This proposal will provide major inisght to calcium handling in adult and pathological conditions (i.e. heart failure). This overall goal will be accomplished by separating L-type channel dependent and independent diastolic sparks. Understanding spark inititiation could lead to discovering a therapuetic target for cardiac arrhythmias. I will use fast-scanning 2D confocal imaging to study the amplitude, rate of rise, and kinetics of diastolic calcium sparks in embryonic, adult, and thoracic aortic banded mice (i.e. heart failure model). If time allows or if needed, simultaneous whole patch electrophysiology and calcium imaging can be used to dissect the two populations of diastolic sparks in the adult and their voltage dependence.

描述（由申请人提供）：心室肌细胞中钙的失调在许多心脏病的病理模型中普遍存在，例如心力衰竭和心源性猝死。在稳定状态下，质膜 (PM) 钙进入必须等于质膜钙排出，以维持钙稳态。主要的 PM 进入途径是 L 型 Ca 通道，主要的 PM 排出途径是 Na-Ca 交换器 (NCX)。钙可能在心脏舒张期间通过 PM 泄漏以及通过细胞内储存的钙的单一释放（标记为钙火花）进入细胞质。钠钙交换器在舒张期排出钙有助于膜电位的去极化。因此，舒张期钙通量通过正向模式 NCX 可以引发室性心律失常，并可能导致心源性猝死。舒张火花在维度和位置方面都有很好的特征，但它们如何被触发的机制仍然是个谜。然而，我的试验数据表明，通过 L 型钙通道的钙进入是发育中的小鼠心室肌细胞中发生舒张火花所需的输入。因此，该提案的总体目的是确定舒张期钙火花的触发因素和来源。我的初步数据引导我得出总体驱动假设：L 型钙通道进入触发舒张期钙火花。该提案将为成人和病理条件（即心力衰竭）中的钙处理提供重要见解。这一总体目标将通过分离 L 型通道依赖性和独立舒张火花来实现。了解火花启动可能有助于发现心律失常的治疗靶点。我将使用快速扫描 2D 共焦成像来研究胚胎、成年和胸主动脉带状小鼠（即心力衰竭模型）中舒张期钙火花的幅度、上升速率和动力学。如果时间允许或需要，可以同时使用全斑块电生理学和钙成像来剖析成人的舒张期火花的两个群体及其电压依赖性。