Inhibition by dexamethasone of adrenocorticotrophin and cortisol release induced by intravenous infusion of ATP and dibutyryl cyclic AMP in piglets

The effect of intravenous infusions of ATP and dibutyryl cyclic AMP (DB cyclic AMP) on adrenocorticotrophin (ACTH) and corticosteroid release was investigated in piglets.

A consistent increase of both plasma ACTH and plasma cortisol was observed in response to infusions of 600 mg ATP/h. These responses were abolished by pretreating the animals with dexamethasone. A similar pattern of response was observed with DB cyclic AMP infused intravenously. No response occurred when 100 mg DB cyclic AMP were infused in 1 h, but there was a marked plasma corticosteroid response to an infusion of 600 mg DB cyclic AMP in 1 h. Surprisingly, this response was also abolished by pretreatment with dexamethasone.