POTASSIUM CHANNELS IN THE HEART - CELLULAR, MOLECULAR, AND CLINICAL IMPLICATIONS

Potassium channels are membrane-spanning proteins that regulate the fl ow of potassium ions across the cell membrane. Because of the electroc hemical gradient for potassium ions in almost all cell types, opening of potassium channels causes an efflux of potassium ions that in turn tends to make the interior of the cell more negative than its extracel lular environment. During the last 5 years, there has been a rapidly e xpanding base of information about the structure, function, and pharma cologic regulation of this type of ion channel, and the integration of this information is particularly important to cardiac electrophysiolo gy, where control of potassium efflux is relevant to the design of cla ss-III antiarrhythmic agents and to the understanding of genetic basis of certain disorders. This brief review highlights the functional imp ortance of various potassium channels to the electrophysiology of the heart and presents relevant molecular information about the structures that constitute this important family of integral membrane proteins.