Hepatic metabolism during fasting-refeeding transition in conscious pregnant rabbits.
The aim of the present study was to determine changes induced by pregnancy in the hepatic handling of nutrients during the fasting-refeeding transition. Net hepatic and gut substrate fluxes were determined by the Fick principle in conscious pregnant (day 30) and nonpregnant rabbits in the 2 h after consumption of a mixed meal. Hepatic glucose production was suppressed by approximately 50% in both groups from 15 to 90 min. Pregnant rabbits returned to control levels at 120 min. Pregnant females displayed a larger gut glucose output and a greater arterial hyperglycemia. The hepatic and gut balance of lactate as well as the arterial level was almost unchanged. In pregnant females the hepatic uptake and arterial concentration of free fatty acids (FFA) remained almost unchanged, whereas these measures decreased in nonpregnant females by approximately 55 and approximately 80%, respectively, at 120 min. The decline in hepatic output of beta-hydroxybutyrate was similar in both groups. In pregnant rabbits arterial levels of beta-hydroxybutyrate did not parallel changes in the hepatic release as in nonpregnant females. Pregnant females displayed a greater hyperinsulinemia both in the portal vein and the artery over the first hour. It is concluded that, in pregnant rabbits fed a mixed meal, the ability of the liver to handle glucose is impaired because of insulin resistance. The latter brings about a greater and prolonged arterial hyperglycemia, which is reinforced by peripheral insulin resistance. Furthermore, the higher level of FFA may also contribute to the hyperglycemia. As a result, a greater amount of glucose is diverted to other sites, presumably the uterus.