title: Whole-body and splanchnic amino acid metabolism in sheep during an acute endotoxin challenge.
abstract: Supplemented protein or specific amino acids (AA) are proposed to help animals combat infection and inflammation. The current study investigates whole-body and splanchnic tissue metabolism in response to a lipopolysaccharide (LPS) challenge with or without a supplement of six AA (cysteine, glutamine, methionine, proline, serine and threonine). Eight sheep were surgically prepared with vascular catheters across the gut and liver. On two occasions, four sheep were infused through the jugular vein for 20 h with either saline or LPS from Escherichia coli (2 ng/kg body weight per min) in a random order, plus saline infused into the mesenteric vein; the other four sheep were treated with saline or LPS plus saline or six AA infused via the jugular vein into the mesenteric vein. Whole-body AA irreversible loss rate (ILR) and tissue protein metabolism were monitored by infusion of [ring-2H2]phenylalanine. LPS increased (P<0·001) ILR (+17 %), total plasma protein synthesis (+14 %) and lymphocyte protein synthesis (+386 %) but decreased albumin synthesis (-53 %, P=0·001), with no effect of AA infusion. Absorption of dietary AA was not reduced by LPS, except for glutamine. LPS increased the hepatic removal of leucine, lysine, glutamine and proline. Absolute hepatic extraction of supplemented AA increased, but, except for glutamine, this was less than the amount infused. This increased net appearance across the splanchnic bed restored arterial concentrations of five AA to, or above, values for the saline-infused period. Infusion of key AA does not appear to alter the acute period of endotoxaemic response, but it may have benefits for the chronic or recovery phases.
authors.affiliation: 1Rowett Institute of Nutrition and Health,University of Aberdeen,Foresterhill,Aberdeen AB25 2ZD,UK.
authors.forename: C J
authors.initials: CJ
authors.lastname: McNeil
authors.affiliation: 1Rowett Institute of Nutrition and Health,University of Aberdeen,Foresterhill,Aberdeen AB25 2ZD,UK.
authors.forename: S O
authors.initials: SO
authors.lastname: Hoskin
authors.affiliation: 1Rowett Institute of Nutrition and Health,University of Aberdeen,Foresterhill,Aberdeen AB25 2ZD,UK.
authors.forename: D M
authors.initials: DM
authors.lastname: Bremner
authors.affiliation: 4Biomathematics and Statistics Scotland,Aberdeen AB25 2ZD,UK.
authors.forename: G
authors.initials: G
authors.lastname: Holtrop
authors.affiliation: 1Rowett Institute of Nutrition and Health,University of Aberdeen,Foresterhill,Aberdeen AB25 2ZD,UK.
authors.forename: G E
authors.initials: GE
authors.lastname: Lobley
mesh_terms: D000596:Amino Acids / Q000378:metabolism* / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D001158:Arteries / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism; D019587:Dietary Supplements; D019446:Endotoxemia / Q000188:drug therapy / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D004731:Endotoxins / Q000009:adverse effects*; D004926:Escherichia coli; D005260:Female; D007249:Inflammation / Q000188:drug therapy / Q000209:etiology / Q000378:metabolism* / Q000382:microbiology; D007262:Infusions, Intravenous; D008070:Lipopolysaccharides; D008099:Liver / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism; D008297:Male; D014176:Protein Biosynthesis / Q000187:drug effects; D011506:Proteins / Q000378:metabolism; D012756:Sheep; D013152:Splanchnic Circulation
chemical_list: D000596:Amino Acids; D001798:Blood Proteins; D004731:Endotoxins; D008070:Lipopolysaccharides; D011506:Proteins
keywords: AA amino acids; Amino acids; Endotoxin lipopolysaccharide; FSR factional synthesis rate; ILR irreversible loss rate; LPS lipopolysaccharide; PDV portal-drained viscera; Protein synthesis; Sheep; Splanchnic tissues