[Potassium channels in glial cells]

Abstract

K+ channels play pivotal roles in maintenance of the resting membrane potential, in the regulation of the action potential duration, repolarization of the membrane potential, inhibition of the cellular excitability and transport of K+ across the cell membrane. Various kinds of K+ channels have been cloned. Mammalian K+ channels can be classified into three families according to their number of putative membrane-spanning region, i.e., six-transmembrane type, four-transmembrane type and two-transmembrane type. Each family consists of many members. These K+ channels are differentially expressed in a variety of cells. The membranes of glial cells are mainly permeable to K+. This is because glial cells express an abundant number of K+ channels. Their main function has been supposed to be aspiration and transportation of extracellular K+, which is liberated from neurons by their excitation. This regulatory function of glial cells is proposed as a spatial buffering mechanism of K+. Recently, molecular level studies on K+ channels of glial cells have been initiated. In this review, we will overview the current understanding of the features and function of K+ channels in glial cells.