Voltage-dependent potassium channels in cultured mammalian Schwann cells.
Voltage-dependent ionic currents were recorded from cultured mammalian Schwann cells (rabbits, mice, rats and humans), by a whole-cell voltage-clamp technique to clarify the properties of voltage-dependent K+ currents in Schwann cells of various species. Voltage-dependent K+ channels were classified into 3 groups according to the degree of inactivation and sensitivity to blockade by tetraethylammonium (TEA): (1) little inactivation and TEA sensitivity (rabbit); (2) rapid inactivation and TEA resistance (rat and human); and (3) intermediate degree of both inactivation and sensitivity to TEA (mouse). In rabbit Schwann cells TEA blocked K+ channels predominantly from outside of the cells, while in the other species K+ channels were blocked by TEA inside the Schwann cells. The voltage-dependent K+ channels in different species had different electrophysiological and pharmacological properties, nevertheless the K+ channels in mammalian Schwann cells were similar to those observed in human or murine T-lymphocytes which are very sensitive to blockade by quinine. Although the culture conditions of human Schwann cells were different from those of other species, K+ channels in human Schwann cells were more similar to rat K+ channels than to those of rabbits or mice.
Konishi
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Department of Neurology, Utano National Hospital, Kyoto, Japan.
D000818:Animals; D002478:Cells, Cultured; D006801:Humans; D008564:Membrane Potentials; D051379:Mice; D008807:Mice, Inbred BALB C; D015221:Potassium Channels / Q000502:physiology*; D011803:Quinine / Q000494:pharmacology; D012583:Schwann Cells / Q000502:physiology*; D012584:Sciatic Nerve / Q000166:cytology* / Q000502:physiology; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D011803:Quinine