title: Arginine and ornithine kinetics in severely burned patients: increased rate of arginine disposal.
abstract: Arginine serves multiple roles in the pathophysiological response to burn injury. Our previous studies in burn patients demonstrated a limited net rate of arginine de novo synthesis despite a significantly increased arginine turnover (flux), suggesting that this amino acid is a conditionally indispensable amino acid after major burns. This study used [15N2-guanidino-5,5-2H2]arginine and [5-13C]ornithine as tracers to assess the rate of arginine disposal via its conversion to and subsequent oxidation of ornithine; [5,5-2H2]proline and [5,5,5-2H3]leucine were also used to assess proline and protein kinetics. Nine severely burned patients were studied during a protein-free fast ("basal" or fast) and total parenteral nutrition (TPN) feedings. Compared with values from healthy volunteers, burn injury significantly increased 1) fluxes of arginine, ornithine, leucine, and proline; 2) arginine-to-ornithine conversion; 3) ornithine oxidation; and 4) arginine oxidation. TPN increased arginine-to-ornithine conversion and proportionally increased irreversible arginine oxidation. The elevated arginine oxidation, with limited net de novo synthesis from its immediate precursors, further implies that arginine is a conditionally indispensable amino acid in severely burned patients receiving TPN.
authors.affiliation: Shriners Burns Hospital and Trauma Service, Massachusetts General Hospital, Boston, MA 02114, USA.
authors.forename: Y M
authors.initials: YM
authors.lastname: Yu
authors.forename: C M
authors.initials: CM
authors.lastname: Ryan
authors.forename: L
authors.initials: L
authors.lastname: Castillo
authors.forename: X M
authors.initials: XM
authors.lastname: Lu
authors.forename: L
authors.initials: L
authors.lastname: Beaumier
authors.forename: R G
authors.initials: RG
authors.lastname: Tompkins
authors.forename: V R
authors.initials: VR
authors.lastname: Young
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001120:Arginine / Q000008:administration & dosage / Q000097:blood*; D002056:Burns / Q000097:blood*; D002247:Carbon Isotopes; D003903:Deuterium; D005260:Female; D006801:Humans; D007700:Kinetics; D007930:Leucine / Q000008:administration & dosage / Q000097:blood; D008297:Male; D008875:Middle Aged; D009587:Nitrogen Isotopes; D009952:Ornithine / Q000008:administration & dosage / Q000097:blood*; D010084:Oxidation-Reduction; D010289:Parenteral Nutrition, Total; D011392:Proline / Q000008:administration & dosage / Q000097:blood
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D001120:Arginine; D011392:Proline; D003903:Deuterium; D009952:Ornithine; D007930:Leucine