Influence of a flooding dose of valine on key indicators of metabolic status in the growing pig.
A key concern with the flooding dose technique for measuring protein synthesis is that a large dose of amino acid (AA) can potentially change the animals' hormonal and nutritional status, which in turn can influence protein synthesis. Among stable isotope tracers, 1-[(13)C]-valine is the preferred AA for measuring protein synthesis in gut tissue and mucins. A study was conducted to determine the impact of a flooding dose of valine on the metabolic status of pigs. Six barrows [16.5 kg body weight (BW)] were randomly assigned to intravenous infusions of either 150 mM valine (1.5 mmol/kg BW) or physiological saline, following a crossover design. Blood samples were taken 10 min prior to infusion, at the end of infusion, at 10-min intervals for 60 min post-infusion, and at 90 and 120 min post-infusion. Plasma concentrations of insulin, glucose, AA, urea nitrogen and packed cell volume (PCV) were measured. Infusion of valine increased plasma valine concentrations (4129 vs. 582 μM; P < 0.05) but had no influence on PCV (26.4% vs. 27.2%) and plasma concentrations of glucose (6.0 vs. 5.8 mM) and insulin (8.2 vs. 8.5 μU/ml; P > 0.10). Plasma urea nitrogen concentration was reduced with valine infusion (8.5 vs. 7.8 mg/dl; P < 0.05). A flooding dose of valine had no impact on plasma concentrations of AA, and specifically branched-chain AA such as leucine (240 vs. 231 μM) and isoleucine (310 vs. 331 μM; P > 0.10). There was, however, a slight increase in the plasma concentrations of threonine (224 vs. 263 μM; P < 0.05) and a tendency towards reduced glycine (1387 vs. 1313 μM; P < 0.10). The results indicate that a flooding dose of valine does not cause a substantial change in the metabolic status of growing pigs and is therefore suitable for measuring protein synthesis rates.
Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada.
A J
AJ
Libao-Mercado
Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada.
D
D
Columbus
Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada.
C F M
CFM
de Lange
D000596:Amino Acids / Q000097:blood / Q000378:metabolism; D000818:Animals; D015415:Biomarkers; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism; D006400:Hematocrit; D008297:Male; D013552:Swine / Q000254:growth & development / Q000378:metabolism*; D014633:Valine / Q000008:administration & dosage / Q000494:pharmacology*
D000596:Amino Acids; D015415:Biomarkers; D014633:Valine
flooding dose; growing pig; metabolic status; protein synthesis; valine