Glutamine carbon disposal and net glutamine uptake in fetuses of fed and fasted ewes.
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.
Levitsky
L L
LL
Pediatric Endocrine Unit, Massachusettes General Hospital, Harvard Medical School, Boston 02114.
Stonestreet
B S
BS
Mink
K
K
Zheng
Q
Q
D000704:Analysis of Variance; D000818:Animals; D002250:Carbon Radioisotopes; D004435:Eating; D005215:Fasting; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005333:Fetus / Q000378:metabolism*; D005973:Glutamine / Q000097:blood / Q000378:metabolism*; D007700:Kinetics; D008431:Maternal-Fetal Exchange; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011865:Radioisotope Dilution Technique; D012044:Regression Analysis; D012756:Sheep; D013997:Time Factors
D002250:Carbon Radioisotopes; D005973:Glutamine