Na+ channels are expressed by mammalian retinal glial (Müller) cells.
Müller cells constitute the principal glia of the vertebrate retina. Unlike other types of neuroglial cells such as astrocytes and Schwann cells, Müller cells have not yet been demonstrated to express Na+ channels. Here we present first evidence of Müller cell Na+ currents from voltage-clamp studies in enzymatically isolated cells. Some cells from retinae of cats and dogs, but none from rabbit or guinea-pig retinae, revealed fast and rapidly inactivating inward currents in response to depolarizing voltage steps. The currents reversibly disappeared in Na+ free solutions or under tetrodotoxin (TTX, 1 microM). Activation and inactivation characteristics of these currents were strikingly similar to those of neurone-type Na+ channels.
Carl Ludwig Institute of Physiology, Leipzig University, Germany.
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Chao
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Pannicke
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Reichelt
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Reichenbach
D000818:Animals; D002415:Cats; D004285:Dogs; D004594:Electrophysiology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009457:Neuroglia / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism; D011817:Rabbits; D012160:Retina / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism*; D013045:Species Specificity; D013779:Tetrodotoxin / Q000494:pharmacology
D015221:Potassium Channels; D015222:Sodium Channels; D013779:Tetrodotoxin