Effect of maternal glucose infusions on fatty acid transport across the placenta in rabbits.

Glucose infusions given intravenously to 28-day-pregnant rabbits increased maternal and fetal plasma immunoreactive insulin levels and decreased maternal concentrations of circulating free fatty acid (FFA). Fetal plasma FFA were only slightly depressed and umbilical venous-arterial concentration differences were unchanged both for total FFA and for individual fatty acids in the FFA fraction. The mean umbilical venous concentration was twice that of maternal levels in the infused group, but about the same concentration in untreated rabbits. It is concluded that the infused glucose, or the high insulin levels provoked by it, or both, caused an increased flow of FFA to the fetus, probably from sources other than the maternal plasma FFA.