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Oral and intravenous phenylalanine kinetics in medium sized, adult mixed hounds
Author(s) -
Shoveller Anna Kate,
Davenport Gary M.,
Robinson Shanna,
Atkinson James L.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a332-b
Subject(s) - dosing , bolus (digestion) , medicine , pharmacokinetics , phenylalanine , blood sampling , zoology , kinetics , intravenous bolus , chemistry , anesthesia , amino acid , biochemistry , biology , physics , quantum mechanics
To validate the use of oral isotope studies in dogs and define phenylalanine (PHE) kinetics, intravenous (IV) and oral bolus dosing studies were performed in 5 adult, spayed, mixed hound female dogs. Dogs (~3 yrs, ~22 kg) were fed diets that met or exceeded AAFCO guidelines for individual nutrients. On the day of study, dogs were weighed and a catheter was inserted in the cephalic vein for blood sampling and isotope infusion. Dogs received 25 half hourly meals providing a total of 13 g/kg. After two feedings, blood samples were taken immediately before each feeding for the remainder of the study. After 5 feedings, dogs received either an oral or IV bolus of L‐[1‐ 13 C]PHE (12 mg/kg BW). Oral dosing was accomplished by adding the isotope to the ½ hourly feeding at t0. All dogs received both oral and IV dosing on separate days, 2 weeks apart. Enrichment and concentrations of plasma PHE were measured. Standard equations were used to calculate non‐steady state kinetics. Oral dosing resulted in a greater turnover time (1.403 vs. 0.724 h, P<0.05) and half life (0.972 vs. 0.502 h, P<0.05) than IV dosing. There were no differences in either plasma PHE concentrations (34 μmol/L ± 0.63) or PHE pool size (9.97 μmol/kg ± 0.63) between groups (P>0.05). Together, these data demonstrate that oral isotope dosing can be used in dogs to determine amino acid kinetics, avoiding the use of the more invasive intravenous dosing. Furthermore, PHE kinetics have been defined in the healthy adult, female, mixed hound dog.