Ion channels in glial cells

Functional and molecular analysis of glial voltage- and ligand-gated ion ch annels underwent tremendous boost over the last 15 years. The traditional i mage of the glial cell as a passive, structural element of the nervous syst em was transformed into the concept of a plastic cell, capable of expressin g a large variety of ion channels and neurotransmitter receptors. These mol ecules might enable glial cells to sense neuronal activity and to integrate it within glial networks, e.g., by means of spreading calcium waves. In th is review we shall give a comprehensive summary of the main functional prop erties of ion channels and ionotropic receptors expressed by macroglial cel ls, i.e., by astrocytes, oligodendrocytes and Schwann cells. In particular we will discuss in detail glial sodium, potassium and anion channels, as we ll as glutamate, GABA and ATP activated ionotropic receptors. A majority of available data was obtained from primary cell culture, these results have been compared with corresponding studies that used acute tissue slices or f reshly isolated cells. In view of these data, an active glial participation in information processing seems increasingly likely and a physiological ro le for some of the glial channels and receptors is gradually emerging. (C) 2000 Elsevier Science B.V. All rights reserved.