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Determination of glutamate requirement in growing rats by indicator amino acid oxidation
Author(s) -
Sakai Ryosei,
Kuwahara Tomomi,
Kawamata Yasuko,
Uneyama Hisayuki,
Torii Kunio,
Nakamura Hidehiro
Publication year - 2012
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.26.1_supplement.1013.25
Subject(s) - amino acid , leucine , chemistry , nitrogen balance , food intake , food science , metabolism , biochemistry , composition (language) , nitrogen , zoology , biology , endocrinology , organic chemistry , linguistics , philosophy
Although many studies have investigated requirements for essential amino acids both in animals and human, few have done for non‐essential amino acids (NEAAs). This study aimed to determine requirement for glutamate (Glu), the most abundant NEAA in food proteins, in growing rats by the indicator amino acid oxidation (IAAO) method. Wistar strain male rats (6wks old) were given fixed amount of diets containing varied doses of amino acid (AA) mixture with NRC 1995 composition (56–214 g/kg) hourly. Dietary labeling with an indicator AA ([1‐ 13 C]leucine) started at 3h of feeding period and 13 C‐enrichments of breath CO 2 were monitored. Relation between dietary AA contents and IAAO (= average 13 C‐enrichments from 4 to 7h) was analyzed to determine a breakpoint as its requirement. Similarly, relation between dietary Glu content and IAAO was analyzed in rats fed diets containing graded doses of Glu (0–100 g/kg). In both experiments, increase of AA or Glu contents at lower doses reduced IAAO, but did not further at higher doses. Apparent breakpoints were determined in their biphasic relations, indicating 173 and 45 g/kg diet of requirements for AA and Glu, respectively. Glu requirement estimated in this study was almost identical with the value determined by nitrogen‐balance study. These results indicated the existence of Glu requirement and suggested importance of dietary Glu as one of components of protein nutrition.