title: Responses in whole-body amino acid kinetics to an acute, sub-clinical endotoxin challenge in lambs.
abstract: Some effects of parasitism, endotoxaemia or sepsis can be mitigated by provision of extra protein. Supplemented protein may encompass a metabolic requirement for specific amino acids (AA). The current study investigates a method to identify and quantify the amounts of AA required during inflammation induced by an endotoxin challenge. One of each pair of six twin sheep was infused in the jugular vein for 20 h with either saline (control) or lipopolysaccharide (LPS, 2 ng/kg body weight per min) from Escherichia coli. Between 12 and 20 h a mixture of stable isotope-labelled AA was infused to measure irreversible loss rates. From 16 to 20 h all sheep were supplemented with a mixture of unlabelled AA infused intravenously. Blood samples were taken before the start of infusions, and then continuously over intervals between 14 and 20 h. At 20 h the sheep were euthanised, and liver and kidney samples were taken for measurement of serine-threonine dehydratase (SDH) activity. LPS infusion decreased plasma concentrations of most AA (P<0·05; P<0·10 for leucine and tryptophan), except for phenylalanine (which increased P=0·022) and tyrosine. On the basis of the incremental response to the supplemental AA, arginine, aspartate, cysteine, glutamate, lysine (tendency only), glycine, methionine, proline, serine and threonine were important in the metabolic response to the endotoxaemia. The AA infusion between 16 and 20 h restored the plasma concentrations in the LPS-treated sheep for the majority of AA, except for glutamine, isoleucine, methionine, serine and valine. LPS treatment increased (P<0·02) SDH activity in both liver and kidney. The approach allows quantification of key AA required during challenge situations.
authors.affiliation: 1Rowett Institute of Nutrition and Health,University of Aberdeen,Greenburn Road,Bucksburn,Aberdeen AB21 9SB,UK.
authors.forename: S O
authors.initials: SO
authors.lastname: Hoskin
authors.affiliation: 1Rowett Institute of Nutrition and Health,University of Aberdeen,Greenburn Road,Bucksburn,Aberdeen AB21 9SB,UK.
authors.forename: D M
authors.initials: DM
authors.lastname: Bremner
authors.affiliation: 2Biomathematics and Statistics Scotland,Aberdeen AB21 9SB,UK.
authors.forename: G
authors.initials: G
authors.lastname: Holtrop
authors.affiliation: 1Rowett Institute of Nutrition and Health,University of Aberdeen,Greenburn Road,Bucksburn,Aberdeen AB21 9SB,UK.
authors.forename: G E
authors.initials: GE
authors.lastname: Lobley
mesh_terms: D000596:Amino Acids / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D000824:Animal Nutritional Physiological Phenomena / Q000187:drug effects; D000818:Animals; D003433:Crosses, Genetic; D004305:Dose-Response Relationship, Drug; D019446:Endotoxemia / Q000097:blood / Q000276:immunology / Q000378:metabolism / Q000662:veterinary*; D004926:Escherichia coli / Q000276:immunology; D004927:Escherichia coli Infections / Q000097:blood / Q000276:immunology / Q000378:metabolism / Q000662:veterinary*; D005260:Female; D007262:Infusions, Intravenous; D007668:Kidney / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D007700:Kinetics; D012695:L-Serine Dehydratase / Q000378:metabolism; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000633:toxicity; D008099:Liver / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D008297:Male; D016555:Matched-Pair Analysis; D009751:Nutritional Requirements; D010865:Pilot Projects; D012756:Sheep; D012757:Sheep Diseases / Q000097:blood / Q000276:immunology / Q000378:metabolism*; D034561:Sheep, Domestic
chemical_list: D000596:Amino Acids; D008070:Lipopolysaccharides; D012695:L-Serine Dehydratase
keywords: AA amino acid; Amino acids; BW body weight; Endotoxin lipopolysaccharide; ILR irreversible loss rates; Irreversible loss rate; SDH serine-threonine dehydratase; Serine-threonine dehydratase; Sheep