The influence of glycogen level on hepatic glucose efflux in the anesthetized rat

This study was initiated to study the effect of a number of physiological conditions on the flux of metabolites across the liver. It was observed that there was a rather high rate of hepatic glycogen depletion in the anesthetized rat and this preparation was used to investigate the relationship between the rate of hepatic glycogenolysis and the level of glycogen in the liver. To produce a range of liver glycogen levels, rats were either ad libitum fed or 8- or 24-hr fasted. In addition, half of each group was anesthetized for either 10 or 70 min. Glucose flux across the liver was determined by measuring blood flow and glucose concentrations in the portal vein, hepatic artery, and hepatic vein. The rate of glycogen depletion and glucose efflux were greatest in the ad libitum fed animals and lowest in the 24-hr fasted rats. In all three groups glucose efflux was lower after 70 min of anesthesia than after 10 min. The results of this study demonstrate that anesthesia causes a rather high rate of hepatic glycogenolysis and the rate of glycogenolysis is decreased as the liver glycogen level is lowered.