[Control activities and regulation by the glucocorticoids of three urea-cycle enzymes in rat foetal liver: argininosuccinate synthetase, argininosuccinase and arginase (author's transl)].

The activity of three urea-cycle enzymes, argininosuccinate synthetase, argininosuccinase and arginase have been studied in the foetal and new-born liver of rats. The activity increases with regularity between 17.5 days of pregnancy and birth in control foetuses. The lack of corticosteroid from 18.5 days of pregnancy decreases the activity of argininosuccinate synthetase. After administration of cortisol (hydrocortisone), to these 18.5 day-old foetuses lacking of corticosteroids, both activities of argininosuccinate synthetase and arginase are enhanced.