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UPTAKE OF AMINO ACIDS AND AMMONIA AT MID‐GESTATION BY THE FETAL LAMB
Author(s) -
Bell Alan W.,
Kennaugh Jan M.,
Battaglia Frederick C.,
Meschia Giacomo
Publication year - 1989
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1989.sp003316
Subject(s) - valine , amino acid , fetus , glutamine , leucine , alanine , isoleucine , glycine , gestation , medicine , biology , placenta , arginine , biochemistry , endocrinology , chemistry , pregnancy , genetics
Fetal uptakes of amino acids and ammonia via the umbilical circulation were measured in single pregnant ewes at mid‐gestation (range 66‐81 days). There were significant net fluxes from placenta to fetus of ammonia and twelve amino acids (in decreasing order: glutamine, glycine, alanine, proline, lysine, arginine, threonine, valine, leucine, tyrosine, asparagine, isoleucine) and net fluxes from fetus to placenta of glutamate and serine. The estimated serine flux was 139 µmol day −1 (g fetal dry wt) −1 . Comparison with late gestation data indicated a similar pattern of amino acid exchange. However, the relatively large placental uptake of fetal serine was a distinctive feature of mid‐gestation. The net fetal uptake of amino acid nitrogen was 2·83 ± 0·66 µg N (µmol O 2 uptake) −1 , or 18 mg N day −1 (g dry wt) − . This uptake was similar in magnitude to the combined fetal requirements for nitrogen accretion and urea synthesis and represented approximately 32 and 43% of fetal carbon and energy requirements, respectively.