GLUCOSE, LACTATE AND OXYGEN-METABOLISM IN THE FETAL PIG DURING LATE-GESTATION

Using [U-C-14]glucose tracer, rates of umbilical uptake, utilization a nd production of glucose, and of CO2 production from glucose carbon, w ere measured in seven chronically catheterized fetal pigs, when the so w was in the fed state, between 100 and 113 days of gestation (term, 1 14 +/- 2 days). At the same time, rates of umbilical O-2 and lactate u ptake were determined in all seven fetuses by the Fick principle. The mean fetal rates of umbilical glucose uptake, glucose utilization and CO2 production from glucose carbon were 38.4 +/- 4.2, 41.3 +/- 5.2 and 126.9 +/- 12.6 mu mol min(-1) (kg fetal body weight)(-1), respectivel y (n = 7). No glucose production was therefore detected in the fetuses . Production of CO2 from glucose carbon accounted for 37.3 +/- 34% (n = 7) of the umbilical O-2 uptake, which averaged 340 +/- 13 mu mol min (-1) kg(-1) (n = 7). There was also significant umbilical lactate upta ke in the fetal piglets when the sow was in the fed stale (32.6 +/- 10 .4 mu mol min(-1) kg(-1), n = 7, P < 0.05). No significant changes in fetal glucose, O-2 or lactate metabolism were observed with increasing age towards term. The fetal rates of glucose metabolism and of umbili cal uptake of O-2 and lactate were not correlated with the fetal blood glucose level. Hence, glucose is used for both oxidative and non-oxid ative metabolism in utero and is an important, although not the sole, source of carbon for metabolic processes in the fetal pig during late gestation.