AJP - Endocrinology and Metabolism, Vol 265, Issue 5 E722-E727, Copyright © 1993 by American Physiological Society

ARTICLES

Glutamine carbon disposal and net glutamine uptake in fetuses of fed and fasted ewes

L. L. Levitsky, B. S. Stonestreet, K. Mink and Q. Zheng
Pediatric Endocrine Unit, Massachusettes General Hospital, Harvard Medical School, Boston 02114.

We have traced ovine fetal glutamine carbon uptake and disposal in 7 chronically catheterized fetuses of fed ewes and 10 fetuses of 48-h fasted ewes. Net fetal glutamine uptake (Fick principle, antipyrine blood flow) was 10.0 +/- 2.0 mumol.kg-1 x min-1 in fed fetuses and 6.4 +/- 1.4 mumol.kg-1 x min-1 in fasted fetuses [not significant (NS)]. However, net fetal glutamine uptake was linearly related to the umbilical vein glutamine level (P < 0.05) in fed and fasted fetuses. In contrast, fetal glutamate transfer to the placenta was 4.0 +/- 0.8 mumol.kg-1.min-1 in the fed state and 2.7 +/- 0.1 mumol.kg-1 x min-1 in the fasted state. Net fetal glutamine uptake and fetal glutamate transfer to the placenta were directly correlated (P < 0.05). Fetal glutamine carbon disposal was measured using a primed continuous infusion of [U-14C]-glutamine over a 3-h period and blood sampling during the last hour of infusion (steady state). Disposal was 20.9 +/- 2.6 mumol.kg-1 x min-1 in the fed state and 18.6 +/- 2.3 mumol.kg-1 x min-1 in the maternal fasted state (NS). Glutamine carbon disposal did not correlate with fetal arterial glutamine levels and was not influenced by maternal nutritional state.

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