title: Plasma arginine, citrulline, and ornithine kinetics in adults, with observations on nitric oxide synthesis.
abstract: The plasma fluxes of ornithine (Orn), arginine (Arg), and citrulline (Cit) and rate of conversion of labeled ornithine-to-citrulline (QOrn-->Cit) were estimated in six healthy adult men receiving an arginine-rich or arginine-free L-amino acid-based diet, each for 6 days. On day 7 an 8-h (3-h fast, 5-h fed) primed continuous intravenous infusion of L-[guanido-15N,15N] arginine, L-[ureido-13C]citrulline, L-[5,5,2H2]ornithine, and L-[5,5,5-2H3]leucine was conducted. Mean citrulline fluxes (mumol.kg-1.h-1) were 10.4-13.6 for the various conditions and/or diets and remained unchanged (P > 0.05). Arginine flux was lowered (P < 0.01) by 38% for fed state during arginine-free period. Ornithine fluxes for arginine-rich were (P < 0.01) reduced with the arginine-free diet. Rates of QOrn-->Cit declined by 30% (P < .05) during the fed arginine-free period. Short-term restriction in the dietary supply of arginine did not alter the rate of whole body nitric oxide synthesis. One subject showed a very high output of nitrate on arginine-free diet (6 times average for remaining subjects).
authors.affiliation: Laboratory of Human Nutrition, School of Science, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: L
authors.initials: L
authors.lastname: Castillo
authors.forename: M
authors.initials: M
authors.lastname: Sánchez
authors.forename: J
authors.initials: J
authors.lastname: Vogt
authors.forename: T E
authors.initials: TE
authors.lastname: Chapman
authors.forename: T C
authors.initials: TC
authors.lastname: DeRojas-Walker
authors.forename: S R
authors.initials: SR
authors.lastname: Tannenbaum
authors.forename: A M
authors.initials: AM
authors.lastname: Ajami
authors.forename: V R
authors.initials: VR
authors.lastname: Young
mesh_terms: D000328:Adult; D001120:Arginine / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology; D002956:Citrulline / Q000097:blood*; D004032:Diet; D005215:Fasting; D006706:Homeostasis; D006801:Humans; D007700:Kinetics; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D009587:Nitrogen Isotopes; D009952:Ornithine / Q000097:blood*
chemical_list: D009587:Nitrogen Isotopes; D002956:Citrulline; D009569:Nitric Oxide; D001120:Arginine; D009952:Ornithine