Differential distribution of cardiac ion channel expression as a basis for regional specialization in electrical function.
The cardiac electrical system is designed to ensure the appropriate rate and timing of contraction in all regions of the heart, which are essential for effective cardiac function. Well-controlled cardiac electrical activity depends on specialized properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Cardiac electrical specialization was first recognized in the mid 1800s, but over the past 15 years, an enormous amount has been learned about how specialization is achieved by differential expression of cardiac ion channels. More recently, many aspects of the molecular basis have been revealed. Although the field is potentially vast, an appreciation of key elements is essential for any clinician or researcher wishing to understand modern cardiac electrophysiology. This article reviews the major regionally determined features of cardiac electrical function, discusses underlying ionic bases, and summarizes present knowledge of ion channel subunit distribution in relation to functional specialization.
Schram
Gernot
G
Department of Medicine, University of Montreal, Research Center, Montreal Heart Institute, Quebec, Canada.
Pourrier
Marc
M
Melnyk
Peter
P
Nattel
Stanley
S
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001283:Atrioventricular Node / Q000502:physiology; D015870:Gene Expression; D006321:Heart / Q000502:physiology*; D006801:Humans; D007473:Ion Channels / Q000235:genetics / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism*; D012849:Sinoatrial Node / Q000502:physiology
D007473:Ion Channels