Our data indicate that K ir channel expression is elevated in week 3 O4+‐oligodendrocytes above that seen in week 1 O4+‐oligodendrocytes and OPCs and correlates well with a hyperpolarization of the RMP of week 3 O4+‐oligodendrocytes. Indeed expression of inwardly rectifying K ir4.1 subunits in oligodendrocytes is critical to their maturation and their ability to myelinate in vivo 29. In addition, upregulation of K ir4.1 subunits has been proposed to allow OPCs in the adult brain to sense local changes in K+ concentrations generated by neuronal activity 30.
