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J Neurosci. 1997 Apr 15;17(8):2669-82.

K+ channel expression and cell proliferation are regulated by intracellular sodium and membrane depolarization in oligodendrocyte progenitor cells.

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  • 1Laboratory of Cellular and Molecular Neurophysiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4495, USA.

Abstract

The effects of a variety of antiproliferative agents on voltage-dependent K+ channel function in cortical oligodendrocyte progenitor (O-2A) cells were studied. Previously, we had shown that glutamate receptor activation reversibly inhibited O-2A cell proliferation stimulated by mitogenic factors and prevented lineage progression by attenuating outward K+ currents in O-2A cells. We now show that the antiproliferative actions of glutamate receptor activation are Ca2+-independent and arise from an increase in intracellular Na+ and subsequent block of outward K+ currents. In support of this mechanism, agents that acted to depolarize O-2A cells or increase intracellular sodium similarly had an antiproliferative effect, attributable at least in part to a reduction in voltage-gated K+ currents. Also, these effects were reversible and Ca2+-independent. Chronic treatment with glutamate agonists was without any long-term effect on K+ current function. Cells cultured in elevated K+, however, demonstrated an upregulation of inward rectifier K+ currents, concomitant with an hyperpolarization of the resting membrane potential. This culture condition therefore promoted a current phenotype typical of pro-oligodendroblasts. Finally, cells chronically treated with the mitotic inhibitor retinoic acid displayed a selective downregulation of outward K+ currents. In conclusion, signals that affect O-2A cell proliferation do so by regulating K+ channel function. These data indicate that the regulation of K+ currents in cells of the oligodendrocyte lineage plays an important role in determining their proliferative potential and demonstrate that O-2A cell K+ current phenotype can be modified by long-term depolarization of the cell membrane.

PMID:
9092588
[PubMed - indexed for MEDLINE]
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