Horio Y, Kurachi Y
Department of Pharmacology II, Faculty of Medicine, Osaka University, Japan.
Nihon Yakurigaku Zasshi. 1997 Mar;109(3):103-10.
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.
钾离子通道在维持静息膜电位、调节动作电位持续时间、膜电位复极化、抑制细胞兴奋性以及钾离子跨细胞膜转运等方面发挥着关键作用。多种类型的钾离子通道已被克隆。哺乳动物的钾离子通道可根据其假定的跨膜区域数量分为三个家族，即六跨膜型、四跨膜型和两跨膜型。每个家族都由许多成员组成。这些钾离子通道在多种细胞中差异表达。神经胶质细胞膜主要对钾离子通透。这是因为神经胶质细胞表达大量的钾离子通道。其主要功能被认为是摄取和转运细胞外钾离子，这些钾离子是由神经元兴奋释放出来的。神经胶质细胞的这种调节功能被提出作为钾离子的空间缓冲机制。最近，已开始对神经胶质细胞的钾离子通道进行分子水平研究。在本综述中，我们将概述目前对神经胶质细胞中钾离子通道的特征和功能的理解。
