Glioma cell influence on cerebral endothelial cell Na(+)-K(+)-ATPase

Using in vitro techniques, we have shown that astrocytes do not increase the ouabain-sensitive Na(+)-K(+)-ATPase activity in cerebral endothelial cells. However, malignant astrocytoma cells when co-cultured with cerebral endothelial cells significantly enhance ouabain-sensitive Na(+)-K(+)-ATPase activity in cerebral endothelial cells. Also, Na(+)-K(+)-ATPase activity in cerebral endothelial cells co-cultured with malignant astrocytoma cells is inhibited by corticosteroids to the same degree as ouabain. These results suggest that brain edema associated with malignant glioma may in part be due to an increase in ouabain-sensitive Na(+)-K(+)-ATPase activity at the blood-brain barrier and that the antiedema effects of corticosteroids may be due to a reduction in the activity of this enzyme.