Etude in vivo chez le rat de l'influence du glucose et du fructose sur le métabolisme intestinal et hépatique

Summary. Influence of glucose and fructose on intestinal and hepatic metabolism in the rat in vivo. Intestinal and hepatic metabolism has been studied in rats fed 12-day diets comprising 74 p. 100 of either glucose or fructose. Food was available during 8 hrs, and tissue was sampled on anesthetized animals 6 hrs after the beginning of food intake. In the digestive tract, fructose was poorly converted into glucose (less than 10 p. 100), and enterocyte lactate production was similar with both hexoses, representing less than 10 p. 100 of the absorbed carbohydrates. About 50 p. 100 of the absorbed glucose was taken up by the liver, as against more than 90 p. 100 of the fructose. Considering the transformation of fructose into glucose, the hepatic carbohydrate balance was very similar with the two diets in our sampling condi- tions. Decreased liver uptake of lactate accounted for the increased lactataemia with the fructose diet. This fact was possibly due to an increase of hepatic triose phosphate and pyru- vate production, as fructose was mainly utilized in the fructose-1 phosphate pathway. Depletion of the hepatic ATP, induced by acute administration of fructose, was not observed in our adapted rats. As glycogen storage was more rapid with the fructose diet, triglyceride synthesis (an alternative pathway for the utilization of carbohydrates) certainly increased. This fact could account for the higher plasma triglycerides with the fructose diet, possibly associated with a lower response to the circulating insulin.