Regulation of intracellular protein degradation in the isolated perfused liver of the chicken (Gallus domesticus).

1. The effects of insulin, glucagon and a supply of exogenous amino acids on protein degradation have been studied in isolated perfused livers from growing chickens by measuring the rate of net valine release in the presence of cycloheximide. 2. Insulin inhibited protein degradation as did a supply of exogenous amino acids. 3. Addition of glucagon increased uric acid release from the livers but had no significant effect on protein degradation. 4. When the effects of the hormones and amino acid mixture are compared with published data for the rat it is evident that the action of glucagon differs in the two species.