CHLORIDE-ION CHANNELS IN MAMMALIAN HEART-CELLS

An explosion of interest in and information about cardiac Cl− channels in recent years now promises to enhance the understanding of cardiac anion channels. Whereas, until recently, the very existence of any cardiac Cl− channel has been controversial, there is now strong electrophysiological evidence for at least three kinds of cardiac Cl− channels and molecular biological evidence suggests that there could be at least two more. This chapter discusses the latest developments, contributing to the understanding of the distribution, regulation, biophysical characteristics, and functions of the various cardiac Cl− channel types, in an attempt to minimize duplication with recent comprehensive reviews of this subject. The application of patch-clamp techniques to cardiac myocytes has provided convincing evidence for the existence of at least three kinds of cardiac Cl− channel. The differences in their regulatory mechanisms suggest that each might play a distinct role in modulating the resting membrane potential or the action potential of myocytes according to the circumstances, depending, for example, on whether there are circulating catecholamines or there is cell swelling or release of Ca2+ from the sarcoplasmic reticulum. © 1994, Academic Press, Inc.