Abstract
Previous studies of gluconeogenic capability of the fetus in vivo have yielded conflicting results, and the specific role of the fetal liver in gluconeogenesis has not been defined. We studied 7 fetal lambs with mean gestational age 130.5 days (range 122-140d). We placed catheters in maternal artery and vein and in fetal hindlimb artery (FA) + vein (IVC), right or left hepatic vein (RHV, LHV), and umbilical vein (UV). After 3-5 days recovery, 14C-alanine (25 μCi bolus, 20 μCi/hr continuous infusion) or 14C-lactate (40 μCi bolus, 30 μCi/hr continuous infusion) was infused into fetal IVC. Lactate and glucose concentrations, glucose specific activity, and substrate radioactivity were measured after 30 and 60 minutes. Radioactive microspheres were injected into UV to measure liver blood flow. 14C-Glucose uptake and release by the liver was calculated; net labelled glucose was calculated as a percentage of 14C-substrate perfusing the liver. Mean glucose uptake from the placenta was 6.00 mg/kg/min (range 2.13-16.0). Glucose uptake or release by each liver lobe was only 0.70 mg/min; (range -3.7 to 9.5). Only 0.35% (range 0-2.3%) of 14C-substrate was converted to 14C-glucose; 14C-lactate (0.29%) and 14C-alanine (0.38%) were not significantly different. There was a suggestion that the left lobe converted less substrate to glucose (0.03%) than did the right (0.48%).
We conclude that hepatic gluconeogenesis contributes negligibly to fetal glucose supply. Warnes et al. showed gluconeogenesis is present within minutes after birth. Our model permits the evaluation, in utero, of mechanisms that stimulate gluconeogenesis.
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Gleason, C., Rudolph, A. NEGLIGIBLE GLUCONEOGENESIS BY THE FETAL LAMB LIVER. Pediatr Res 18 (Suppl 4), 138 (1984). https://doi.org/10.1203/00006450-198404001-00271
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DOI: https://doi.org/10.1203/00006450-198404001-00271