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Sodium Dependent Inactivation of the Na+-Ca2+ exchange: Relevance to Cardiac Function

Na-Ca2 交换的钠依赖性失活：与心脏功能的相关性

基本信息

批准号：
10531590
负责人：
Riccardo Olcese
金额：
$ 54.61万
依托单位：
UNIVERSITY OF CALIFORNIA LOS ANGELES
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-12-18 至 2024-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10531590
关键词：
Action Potentials Address Adult Affect Allosteric Regulation Animals Anti-Arrhythmia Agents CRISPR/Cas technology Calcium Cardiac Cardiac Myocytes Cardiac health Cell membrane Cells Cessation of life Clustered Regularly Interspaced Short Palindromic Repeats Congestive Heart Failure Coupling Cytoplasm Darkness Data Development Drug Targeting Echocardiography Electrophysiology (science)Equilibrium Event Excision Genes Genomics Goals Heart Heart Contractilities Heart failure Homeostasis Hypertrophy Imaging Techniques Investigation Ions Ischemia Knowledge Link Measures Membrane Potentials Membrane Proteins Modification Mus Muscle Cells Mutate Mutation Myocardial Ischemia Organ Pathologic Perception Perfusion Phase Physiological Physiology Play Process Property Proteins Regulation Reperfusion Injury Reperfusion Therapy Research Research Personnel Role Route Shapes Site Sodium Sodium-Calcium Exchanger Spottings System Ventricular Work design electrical property extracellular heart function in vivo inhibitor mechanical properties novel novel therapeutic intervention novel therapeutics operation pharmacologic response

项目摘要

PROJECT SUMMARY/ABSTRACT Na+ and Ca2+ ion homeostasis are essential for heart excitability and contractility. At the cellular level the plasma membrane protein Na+-Ca2+ exchanger (NCX) plays a vital role in regulating the ionic homeostasis of both Na+ and Ca2+. It does so by extruding one Ca2+ out of the cell in exchange for three extracellular Na+ ions. In addition to being transported, both these ions allosterically regulate the activity of NCX. Intracellular Ca2+ increases NCX activity while cytoplasmic Na+ inactivates NCX via a process known as Na+-dependent inactivation. Despite the potential physiological and pathophysiological relevance of this regulation, whether the Na+-dependent inactivation occurs in vivo is unknown and its impact has yet to be determined. Since this is such an exquisite controlling system, but heretofore uninvestigated, the investigators hypothesize that small changes in cellular Na+ concentrations may have significant effects on Ca2+ homeostasis by directly affecting NCX activity and thereby affect excitability and contractility of the heart. Therefore, the goal of this application is to investigate the physiological impact of NCX Na+ modulation and determine how it ultimately shapes heart contractility. These studies have been hampered by the difficulties of studying this process in intact myocytes under controlled conditions. However, with the development of genomic modification via CRISPR technology, this experimental paradigm, heretofore out of reach, can now be addressed. Using CRISPR, the investigators have inserted a single site mutation (K229Q) in the native cardiac NCX gene of mice, which will exclusively abolish Na+- dependent inactivation. By combining electrophysiology and calcium imaging techniques, the collected novel preliminary data demonstrating that the inhibition of NCX by cytoplasmic Na+ alters the electrical and mechanical properties of both single cells and intact hearts. The work proposed here is organized into two aims. Aim 1 will investigate how the absence of Na+-dependent inactivation alters excitation-contraction coupling in mouse adult ventricular myocytes by comparing, action potentials, Ca2+ transients and ionic currents measured from adult ventricular myocytes isolated from either control (WT) or the genetically altered mice (K229Q). Aim 2 will conduct similar recordings but in intact perfused hearts. Additionally, the cardiac function of live K229Q mice will be assessed using echocardiography. These investigations are groundbreaking as they will detail the potential function of NCX allosteric Na+ regulation in cardiac function. This work may also have pathophysiological applications by defining the regulation of Na+ as a potential target for controlling NCX activity.

项目总结/文摘