Arginine Can Be Synthesized from Enteral Proline in Healthy Adult Humans  

Oleh:

Tomlinson, Chris ; Rafii, Mahroukh ; Ball, Ronald O. ; Pencharz, Paul B.

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: JN: The Journal of Nutrition vol. 141 no. 08 (Aug. 2011), page 1432-1436 .
Topik: Biochemical; Molecular; Genetic Mechanisms

Ketersediaan

Perpustakaan FK Nomor Panggil: J42.K.2011.02 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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Isi artikel

There is considerable controversy recently in identifying dietary precursors for arginine synthesis. We have previously shown in human neonates and piglets that proline is the sole dietary precursor for arginine synthesis. It is unclear in adult humans whether proline is a dietary precursor for arginine. We performed a multi-tracer stable isotope study in adults using 15N2-ureido arginine and 15N proline to elucidate synthesis of citrulline and arginine and determine whether proline is a precursor for arginine. Primed, intermittent infusions of the labeled amino acids were given enterally to 5 healthy men consuming a standardized milkshake diet. Blood was sampled during plateau enrichment between 1.5 and 3 h. Plasma enrichment occurred for both tracers, giving enteral turnover estimates of 93 µmol · kg-1 · h-1 for arginine and 154 µmol · kg-1 · h-1 for proline. Appearance of the label from proline in arginine and the intermediaries, ornithine and citrulline, was measured in all participants. The rate of synthesis of arginine from proline was 3.7 µmol · kg-1 · h-1, which is estimated to be ~40% of newly synthesized arginine. In this first study in adult humans using an enteral proline tracer, we have demonstrated synthesis of arginine from this dietary amino acid. Therefore, as in newborns, proline must now be considered a dietary precursor for arginine in healthy adults.

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