Regulation of cardiac excitation–contraction coupling by action potential repolarization: role of the transient outward potassium current (Ito)

The cardiac action potential (AP) is critical for initiating and coordinating myocyte contraction. In particular, the early repolarization period of the AP (phase 1) strongly influences the time course and magnitude of the whole‐cell intracellular Ca2+ transient by modulating trans‐sarcolemmal Ca2+...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of physiology 2003-01, Vol.546 (1), p.5-18
Main Authors: Sah, Rajan, Ramirez, Rafael J., Oudit, Gavin Y., Gidrewicz, Dominica, Trivieri, Maria G., Zobel, Carsten, Backx, Peter H.
Format: Article
Language:English
Subjects:
Action Potentials
Animals
Calcium - metabolism
Humans
Models, Cardiovascular
Myocardial Contraction - physiology
Myocardium - metabolism
Potassium Channels - physiology
Sarcoplasmic Reticulum - metabolism
Topical Review
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The cardiac action potential (AP) is critical for initiating and coordinating myocyte contraction. In particular, the early repolarization period of the AP (phase 1) strongly influences the time course and magnitude of the whole‐cell intracellular Ca2+ transient by modulating trans‐sarcolemmal Ca2+ influx through L‐type Ca2+ channels (ICa,L) and Na‐Ca exchangers (ICa,NCX). The transient outward potassium current (Ito) has kinetic properties that make it especially effective in modulating the trajectory of phase 1 repolarization and thereby cardiac excitation‐contraction coupling (ECC). The magnitude of Ito varies greatly during cardiac development, between different regions of the heart, and is invariably reduced as a result of heart disease, leading to corresponding variations in ECC. In this article, we review evidence supporting a modulatory role of Ito in ECC through its influence on ICa,L, and possibly ICa,NCX. We also discuss differential effects of Ito on ECC between different species, between different regions of the heart and in heart disease.
ISSN:0022-3751
1469-7793
DOI:10.1113/jphysiol.2002.026468