Gluconeogenesis from lactate in the chronically catheterized baboon fetus.

Gluconeogenesis from lactate may be qualitatively identified in the chronically catheterized baboon fetus in the maternal fed and fasted state. Infusion of 250 microCi U-14C-lactate to the fetus over a 150-min period leads to the appearance of 14C-glucose in the fetal circulation. Little 14C-lactate or glucose appears in the maternal circulation, supporting fetal production of glucose from lactate. Maternal glucose infusion seems to inhibit fetal gluconeogenesis. The mean plateau in percent disintegrations per minute of glucose compared to lactate in the maternal fed state is 14.7 +/- 2.2 compared to 16.1 +/- 3.0 in the maternal fasting state and 11.1 +/- 0.6 during maternal glucose infusion. It is clear that the primate fetus is capable of gluconeogenesis before term. Quantitation of this capacity awaits development of a model permitting assessment of maternal-placental and fetal substrate flux.