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Glucose Oxygen Uptakes Across Umbilical and Cerebral Circulations of the Fetus

1970; Springer Nature; Volume: 4; Issue: 5 Linguagem: Inglês

10.1203/00006450-197009000-00147

1530-0447

Nicholas G. Tsoulos, James R Colwill, Jack Schneider, Edgar L. Makowski, Giacomo Meschia, Frederick C. Battaglia,

Pregnancy and preeclampsia studies

Glucose has been considered the principal metabolic fuel of the mammalian fetus, but sound experimental evidence is lacking. In this study, the relative contribution of glucose to aerobic metabolism across the umbilical and cerebral circulations of fetal lambs was evaluated. The fetal vessels catheterized were : femoral artery and vein, umbilical vein, subclavian artery and periorbital vein. The arteriovenous differences in glucose and oxygen contents (Δ glucose and Δ oxygen) were determined from simultaneous samples across both circulations. The Δ glucose was expressed as the O2 stoichiometrically required to metabolize glucose to CO2 and H2O. In six chronic, unstressed, unanesthtized animals, the Δ glucose/Δ oxygen ratio across the umbilical circulation during control periods was 0.47 ± 0.04 (mean ± s.e.m.). Fetal infusions of porcine insulin increased the ratio by 90%. We have attempted to compare metabolism in a single organ of the fetus, the brain, with that of the whole fetus (i.e. umbilical circulation) in acute experimetns in seven fetuses. The ratio across the cerebral circulation was 1.5 ± 0.03 and across the umbilical circulation was 0.38 ± 0.03. These data indicate that (a) under normal conditions, glucose supplies a maximum of 50% of the metabolic fule of the fetal lamb, (b) exogenous insulin does affect fetal glucose uptake, and (c) in the acute preparation, the fetal brain utilizes more glucose than can be accounted for by aerobic metabolism.