Myelination in the central nervous system depends on axon-oligodendrocyte precursor cell (OPC) inter- action. We suggest that myelin synthesis may be influenced by [Na+]i and [Ca2+]i signaling in OPCs. Experiments were performed in mouse cultured OPCs at day in vitro (DIV) 2–6 or acute slices of the cor- pus callosum at postnatal days (P) 10–30. Synthesis of Myelin Basic Protein (MBP), an “executive molecule of myelin”, was used as readout of myelination. Immunohistological data revealed that MBP synthesis in cultured OPCs starts around DIV4. Transient elevations of resting [Ca2+ ]i and [Na+ ]i levels were observed in the same temporal window (DIV4-5). At DIV4, but not at DIV2, both extracellular [K+ ] ([K+ ]e) elevation
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were blocked with KB-R7943 (1