Hepatic and intestinal handling of metabolites during feeding in rats.

Changes in hepatic vein, hepatic portal vein and aortal plasma levels of glucose, lactate, nonesterified fatty acids, and D-3-hydroxybutyrate as well as changes in hepatic glycogen and lactate levels were studied during feeding after 12 h of food deprivation in rats. Feeding caused an increase in portal vein lactate concentration and a transient net hepatic lactate uptake that led to hepatic lactate accumulation. As in previous experiments, feeding was associated with hepatic glycogenolysis and net hepatic glucose release, despite a profound increase in portal vein plasma glucose. Net hepatic uptake of nonesterified fatty acids and net hepatic release of D-3-hydroxybutyrate declined during feeding but did not cease, suggesting that hepatic fatty acid oxidation continued throughout feeding. A prandial net intestinal uptake from arterial blood was observed for nonesterified fatty acids and D-3-hydroxybutyrate, while a net intestinal release was found for glucose and lactate. The results are consistent with the idea that under the conditions tested, glucose, lactate and nonesterified fatty acids jointly activate a hepatic metabolic mechanism of satiety.