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Arginine is synthesized from proline not glutamate in enterally fed preterm human infants
Author(s) -
Tomlinson Christopher,
Rafii Mahroukh,
Sgro Michael,
Ball Ron,
Pencharz Paul
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.869.28
Subject(s) - arginine , proline , glutamate receptor , amino acid , glutamic acid , biochemistry , in vivo , chemistry , biology , medicine , receptor , microbiology and biotechnology
Our laboratory recently showed in piglets that proline was the only precursor for de novo synthesis of arginine although in vitro evidence supported glutamate in this role. We performed a multitracer stable isotope study to investigate the immediate precursor for arginine in human neonates. Primed, and intermittent infusion of labeled arginine (M+2), proline (M+1) and glutamate (M+3) were given enterally to four stable, growing preterm infants at 2 weeks of age. Plasma was sampled at 8 and 12 hours during the feeding protocol with urine samples providing the baseline enrichment. The conversion of these amino acids to arginine was measured by LC‐Tandem MS to determine the contribution of each to arginine synthesis. Plateau enrichment of arginine and proline tracers was measured in plasma. Plasma glutamate enrichment was negligible. Significant conversion from proline to arginine was detected. However, the M+3 isotopomer of arginine, which would have been synthesized from glutamate, was not detected. We conclude that, like the piglet, the human neonate only synthesizes arginine from proline, and glutamate is not an arginine precursor in vivo . CIHR supported.