Voltage-dependent potassium channels in mouse Schwann cells.
1. Ionic currents in Schwann cells cultured from enzymatically dissociated sciatic nerves of newborn mice were recorded by the whole-cell variation of the patch-clamp technique. 2. In these cells only the voltage-dependent K+ currents were recorded. The K+ current was suppressed by quinine, 4-aminopyridine (4-AP) or tetraethylammonium (TEA), their half-suppression concentrations being 22 microM, 0.3 mM and 15 mM, respectively. 3. The peak amplitudes and density of the K+ currents in these Schwann cells increased rapidly during the first 2 days of the culture. 4. In an investigation of the linkage between K+ channels and Schwann cell proliferation, three different K+ channel blockers (quinine, 4-AP and TEA) were added to the medium at different stages of the culture. In media containing sublethal doses of quinine or 4-AP, the start of cell proliferation was delayed when these drugs were added at 12 h or on day 3. The same doses of these drugs applied on day 6, when the Schwann cells were proliferating, did not affect cell proliferation. TEA showed a discrepancy between the dose-dependent blocking of K+ channels and cell proliferation because of its additional cytotoxic effects. 5. It is concluded that voltage-dependent K+ channels in mouse Schwann cells are similar to those observed in human and murine T lymphocytes. These K+ channels are suggested to be involved in Schwann cell proliferation at early stages of development.
Konishi
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Department of Neurology, Utano National Hospital, Kyoto, Japan.
D015761:4-Aminopyridine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000831:Animals, Newborn; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D051379:Mice; D015221:Potassium Channels / Q000502:physiology*; D011803:Quinine / Q000494:pharmacology; D012583:Schwann Cells / Q000502:physiology*; D012584:Sciatic Nerve / Q000502:physiology; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D011803:Quinine; D015761:4-Aminopyridine