title: Effect of intravenous glutamine on duodenal mucosa protein synthesis in healthy growing dogs.
abstract: To determine whether glutamine acutely stimulates protein synthesis in the duodenal mucosa, five healthy growing dogs underwent endoscopic biopsies of duodenal mucosa at the end of three 4-h primed, continuous intravenous infusions of L-[1-13C]leucine on three separate days, while receiving intravenous infusion of 1) saline, 2) L-glutamine (800 micromol. kg-1. h-1), and 3) isonitrogenous amounts of glycine. The three infusions were performed after 24 h of fasting, a week apart from each other and in a randomized order. Glutamine infusion induced a doubling in plasma glutamine level, and glycine caused a >10-fold rise in plasma glycine level. During intravenous infusions of [13C]leucine, the plasma leucine labeling attained a plateau value between 3.22 and 3.68 mole % excess (MPE) and [13C]ketoisocaproate ([13C]KIC) of 2.91-2. 84 MPE; there were no significant differences between glutamine, glycine, and saline infusion days. Plasma leucine appearance rate was 354 +/- 33 (SE), 414 +/- 28, and 351 +/- 35 micromol. kg-1. h-1 (not significant) during glycine, saline, and glutamine infusion, respectively. The fractional synthetic rate (FSR) of duodenal mucosa protein was calculated from the rise in protein-bound [13C]leucine enrichment in the biopsy sample, divided by time and with either plasma [13C]KIC or tissue free [13C]leucine as precursor pool enrichment. Regardless of the precursor pool used in calculations, duodenal protein FSR failed to rise significantly during glutamine infusion (65 +/- 11%/day) compared either with saline (84 +/- 18%/day) or glycine infusion days (80 +/- 15%/day). We conclude that 1) plasma [13C]KIC and tissue free [13C]leucine can be used interchangeably as precursor pools to calculate gut protein FSR; and 2) short intravenous infusion of glutamine does not acutely stimulate duodenal protein synthesis in well-nourished, growing dogs.
authors: Centre de Recherche en Nutrition Humaine, Ecole Nationale Vétérinaire de Nantes, 44093 Nantes, France.
authors: J S
authors: JS
authors: Marchini
authors: P
authors: P
authors: Nguyen
authors: J Y
authors: JY
authors: Deschamps
authors: P
authors: P
authors: Maugère
authors: M
authors: M
authors: Krempf
authors: D
authors: D
authors: Darmaun
mesh_terms: D000375:Aging / Q000378:metabolism*; D000596:Amino Acids / Q000097:blood*; D000818:Animals; D000831:Animals, Newborn; D002247:Carbon Isotopes; D004285:Dogs; D004386:Duodenum; D005973:Glutamine / Q000008:administration & dosage / Q000494:pharmacology*; D005998:Glycine / Q000008:administration & dosage / Q000378:metabolism; D007262:Infusions, Intravenous; D007413:Intestinal Mucosa / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D007700:Kinetics; D007930:Leucine / Q000008:administration & dosage / Q000378:metabolism; D014176:Protein Biosynthesis
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D005973:Glutamine; D007930:Leucine; D005998:Glycine