Effects of adrenocortical steroids and of adrenocorticotrophic hormone on (Na+-K+)-ATPase in immature cerebral cortex.

The effect of cortisol, methylprednisolone, and ACTH on (Na+-K+)-ATPase activity in developing cerebral cortex has been measured. Stimulation of (Na+-K+)-ATPase by these agents has been found in whole brain homogenates of kittens as early as age 8 days, and in whole homogenates and light microsomal fractions in young rats at 14 and 28 days. (Na+-K+)-ATPase activity in animals treated with corticosteroids or ACTH for 4 days was found to be 15--30% higher than activity in littermate controls. Brain potassium concentrations was increased in 14-day-old rats treated with methylprednisolone.