Adenosine 3′:5′‐Monophosphate in Perinatal Rat Liver

Developmental changes in the concentration of adenosine 3′:5′-monophosphate (cyclic AMP) and the effects of glucagon and epinephrine were studied in the perinatal rat liver. Hepatic cyclic AMP concentration doubled tha last day gestation. After birth, the cyclic AMP concentraion continuced to increase and maximal levels were observed on the fifthe postnatal day. Surgical deliveray of foetuses on days 20, 21 and 22 of gestation resulted in a rapid increase in cyclic AMP concentration. Maximal concentrations were reached within one hour of delivery in the day-21 and day-22 foetuses. However with surgically delivered day-20 foetuses, the cyclic AMP concentration increased for at least two hours. Glucagon and epinephrine increased the hepatic cyclic AMP concentration in rats deliver3d surgically on days 20, 21 and 22 of gestation and in postnatal rats. Maximal stimulation by epinephrine was observed in 2-day-old rats. Maximal stimulation by glucagon was observed in 10-day-old rats. The rsults support the hypothesis that cyclic AMP is the intracelluar effector for the synthesis of some enzymes in perinatal rat. The cyclic AMP concentration in the perinatal rat liver in vivo appears to be controlled by changes in the relative concentrations of plasma glucagon and insulin.