Molecular Pharmacology, Vol 10, 711-720, Copyright © 1974 by the American Society for Pharmacology and Experimental Therapeutics

Adenosine 3',5'-Monophosphate in Glial Tumor Cells Treated with Glucocorticoids

¹ Department of Pharmacology, College of Medicine and Dentistry of New Jersey, Rutgers Medical School, Piscataway, New Jersey 08854

The effect of various steroids on adenosine 3',5'-monophosphate in C-6 glial tumor cell cultures was examined. Glucocorticoids increased basal and norepinephrine-stimulated concentrations of cyclic AMP in intact cells 2-fold. Exposure of cells to 2 µM corticosterone for at least 48 hr was required to obtain a maximal effect. The concentration of norepinephrine needed for half-maximal activation and the time course of the cyclic AMP response were unaltered. A 2-fold increase in adenylate cyclase activity of broken cell preparations similarly dependent upon corticosterone concentration and time was observed. The apparent K_m for ATP was not changed but the maximum velocity was doubled, suggesting that the steroid induces the synthesis of additional adenylate cyclase. The activity of a second enzyme localized in the surface membrane, (Na⁺ + K⁺)-ATPase, was unaltered in glucocorticoid-treated cells. Also, no differences in the activities of cyclic nucleotide phosphodiesterases were detected.