Molecular Physiology of Cardiac Potassium Channels.
Deal, Karen K., Sarah K. England, and Michael M. Tamkun.
Departments of Molecular Physiology and Biophysics and of Pharmacology,
Vanderbilt University School of Medicine, Nashville, Tennessee.
APStracts 2:0006P, 1996.
ABSTRACT
The cardiac action potential results from the complex, but precisely
regulated, movement of ions across the sarcolemmal membrane. Potassium
channels represent the most diverse class of ion channels in heart and are the
targets of several antiarrhythmic drugs. Potassium currents in the myocardium
can be classified into one of two general categories: [i]1[r]) inward
rectifying currents such as [i]I[inf]K1[r], [i]I[inf]KAch[r], and
[i]I[inf]KATP[r]; and [i]2[r]) primarily voltage-gated currents such as
[i]I[inf]Ks[r], [i]I[inf]Kr[r], [i]I[inf]Kp[r], [i]I[inf]Kur[r], and
[i]I[inf]to[r]. The inward rectifier currents regulate the resting membrane
potential, whereas the voltage-activated currents control action potential
duration. The presence of these multiple, often overlapping, outward currents
in native cardiac myocytes has complicated the study of individual K[sup]+[r]
channels; however, the application of molecular cloning technology to these
cardiovascular K[sup]+[r] channels has identified the primary structure of
these proteins, and heterologous expression systems have allowed a detailed
analysis of the function and pharmacology of a single channel type. This
review addresses the progress made toward understanding the complex molecular
physiology of K[sup]+[r] channels in mammalian myocardium. An important
challenge for the future is to determine the relative contribution of each of
these cloned channels to cardiac function.
APS Manuscript Number P-21-5.
Article publication scheduled January 1996 Physiological Reviews.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96