Differential expression of Na,K-ATPase isoforms in oligodendrocytes and astrocytes

Using Western blot and immunocytochemistry to detect protein, and in situ hybridization and Northern blot to detect RNA, we studied the expression of Na,K-ATPase subunit isoforms in cultured astrocytes and oligodendrocytes in vitro, and in glial cells in the brain. We found that astrocytes in culture express alpha 1 and alpha 2 isoforms of the catalytic subunit and both beta 1 and beta 2 isoforms of the regulatory subunit. Oligodendrocytes in culture express only alpha 1, but in vivo high levels of alpha 2 are seen in oligodendrocytes of white matter tracts. These results suggest that expression of the alpha 2 isoform in mature oligodendrocytes may be regulated by axonal contact and related to myelination.