EFFECTS OF NERVE GROWTH-FACTOR AND DEXAMETHASONE ON NA+,K+-ATPASE OF CULTURED PC12H CELLS

When PC12h cells were cultured for 4 days in the presence of 50 ng/ml of nerve growth factor (NGF), they showed elongated dendrites and specifically increased Na+,K+-ATPase activity. Either singly or in combination with NGF, dexamethasone also increased the specific activity of this enzyme. Western blot analysis using anti-alpha 1 and anti-alpha 2 antisera showed that PC12h cells, either before or after hormone treatment, contained the alpha 1 isoform but not the alpha 2 one. We conclude, therefore, that NGF induces Na+,K+-ATPase concomitantly with neuronal differentiation in PC12h cells but that the growth factor does not induce formation of the myelin sheath, which normally expresses the alpha 2 isoform of Na+,K+-ATPase.