Involvement of Adenosine 3′,5′-Monophosphate in the Activation of Tyrosine Hydroxylase Elicited by Drugs

Immediately after the injection of reserpine (16 micromoles per kilogram, intraperitoneally), aminophylline (200 micromoles per kilogram, intraperitoneally), and carbamylcholine (8.2 micromoles per kilogram, intraperitoneally), the concentration of adenosine 3',5'-monophosphate in adrenal medulla of rats is increased severalfold. The three drugs also cause a delayed increase of medullary tyrosine hydroxylase activity. Our results are consistent with the view that an increase of medullary adenosine 3',5'-monophosphate concentration is involved in the drug-induced increase of tyrosine hydroxylase activity in adrenal medulla. Experiments with tyramine (130 micromoles per kilogram, intraperitoneally) suggest that the increase of tyrosine hydroxylase activity and of adenosine 3',5'-monophosphate concentrations is independent of an increase in adrenal catecholamine turnover rate.