Dietary regulation of pancreatic protein synthesis. II. Kinetics of adaptation of protein synthesis and its effect on enzyme content.

The kinetics of the adaptative changes in the relative rates of synthesis and pancreatic concentrations of amylase, chymotrypsinogen and trypsinogen were studied over 10 days of adaptation to a carbohydrate-rich (G), or a protein-rich (P) diet. During adaptation to the P diet, 60% of the adaptative decrease of the amylase to chymotrypsinogen ratio of incorporation was complete within 24 h of feeding and plateau values were obtained after five days. Adaptation to the G diet was only 20% complete after 24 h and plateau values were obtained later than with the P diet. The evolution of the ratio of concentrations of amylase and chymotrypsinogen followed those of incorporation in the adaptation to both diets. These results support the determinant role of adaptative changes in the rates of synthesis of individual enzymes on the dietary adaptation of enzyme proportions in the pancreas. The differences in the kinetics of adaptation to the two diets suggest that different mechanisms are involved in the adaptative regulation of protein synthesis to a carbohydrate-rich diet or a protein-rich diet.