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Dietary Glutamate Nitrogen Is Exclusively Utilized for Intestinal Production of Amino Acids in Rats
Author(s) -
Nakamura Hidehiro,
Eto Sachise,
Kawamata Yasuko,
Kuwahara Tomomi,
Torii Kunio,
Sakai Ryosei
Publication year - 2011
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.25.1_supplement.983.6
Subject(s) - amino acid , glutamine , metabolism , chemistry , alanine , citrulline , biochemistry , proline , arginine , ornithine , food science , biology , medicine
Dietary glutamate (Glu) has been shown to promote normal growth and wound healing. However it remains unclear how dietary Glu affects systemic conditions, since ingested Glu carbon (C) is exclusively metabolized in the gut. Glu nitrogen (N) is readily transaminated to the other amino acids. Thus, we hypothesized that dietary Glu supplied circulating amino acids‐N via intestinal metabolism. Fischer strain male rats were given hourly meals containing either [U‐ 13 C]Glu or [ 15 N]Glu. Portal and arterial plasma were collected at 0.5, 1, 1.5, 3, 6, 9 h of feeding, and concentrations and isotopic enrichments of individual amino acids were measured. Their net releases from the gut were estimated using their steady state values. Most of Glu‐C and N were metabolized in the gut, and that only minor parts of dietary Glu (both C and N) were released into the portal vein. While 50% of dietary Glu‐C was catabolized to CO 2 , a large part of Glu‐N was found in amino acids such as alanine and citrulline (75% and 8% of dietary Glu‐N, respectively), but not so much in ammonia. These results indicated importance of dietary Glu‐N for intestinal production of amino acids. Further, significant 15 N‐labeling in systemic amino acids such as alanine, citrulline, ornithine, glutamine and proline suggested a substantial contribution of dietary Glu as a nitrogen source also in the whole body.