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Whole body citrulline production, but not arginine production, is increased with aging in healthy humans
Author(s) -
Luiking Yvette C,
Engelen Marielle P,
Vissers Yvonne L,
Deutz Nicolaas E
Publication year - 2006
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.20.4.a160-a
Subject(s) - citrulline , arginine , medicine , endocrinology , metabolism , phenylalanine , chemistry , amino acid , biochemistry
Plasma citrulline (Cit) levels, but not arginine (Arg) levels are related to aging in females. However, whether Cit metabolism is affected by aging and gender is unknown. Therefore we studied whole body Arg and Cit metabolism in relation to age and gender in healthy volunteers. Thirty‐three healthy subjects were studied, according to their age (young (18–25y) vs elderly (50–70y)) or gender (male vs female). Arg and Cit metabolism were measured using primed‐constant (2h) infusion of L[ guanidino ‐15N2]Arg and L‐[ ureido ‐13C‐2H3]Cit. Protein breakdown (PB) was measured as phenylalanine (phe) production using L‐[ ring ‐2H5]phe. Plasma amino acid levels were analysed by HPLC, tracer‐tracee ratios by LC‐MS.When Cit derived de novo Arg production was calculated from Arg production and PB, no age related increase was found. In conclusion, whole body Cit production, but not Arg production, is increased with aging in healthy humans. However, an age dependent adaptation of de novo Arg production seems absent. Therefore, the relevance of increased Cit production with aging requires further study.