Initiation of Glucose 6-Phosphatase Adaptation in the Rat

Abstract

Rats trained to eat for only one hour each day were used to investigate the time required for increases in hepatic glucose 6-phosphatase activity to occur in response to ingestion of high sucrose and high protein diets. Glucose 6-phosphatase activity per unit of body weight decreased during the first few hours after the rats had eaten, regardless of the diet consumed. After 4 hours glucose 6-phosphatase activity of rats fed high protein or high sucrose diets was greater than that of rats fed a 25% casein diet containing dextrin. There was a continuous increase in liver glycogen concentration and relative size in all groups up to 8 hours after they had eaten. Hydrocortisone injection produced a marked increase in liver glycogen concentration and relative size of rats within 8 hours after injection, but had no effect on the glucose 6-phosphatase activity per unit of body weight 8 or 12 hours after injection.