An isotope dilution model for partitioning of phenylalanine and tyrosine uptake by the liver of lactating dairy cows

L.A. Crompton*, L.L. Mcknight, Chris Reynolds, J.A.N. Mills, J.L. Ellis, M.D. Hanigan, J. Dijkstra, B.J. Bequette, A. Bannink, J. France

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)

Abstract

An isotope dilution model to describe the partitioning of phenylalanine (PHE) and tyrosine (TYR) in the bovine liver was developed. The model comprises four intracellular and six extracellular pools and various flows connecting these pools and external blood. Conservation of mass principles were applied to generate the fundamental equations describing the behaviour of the system in the steady state. The model was applied to datasets from multi-catheterised dairy cattle during a constant infusion of [1-13C] phenylalanine and [2,3,5,6-2H] tyrosine tracers. Model solutions described the extraction of PHE and TYR from the liver via the portal vein and hepatic artery. In addition, the exchange of free PHE and TYR between extracellular and intracellular pools was explained and the hydroxylation of PHE to TYR was estimated. The model was effective in providing information about the fates of PHE and TYR in the liver and could be used as part of a more complex system describing amino acid metabolism in the whole animal.
Original languageEnglish
Pages (from-to)100-107
JournalJournal of Theoretical Biology
Volume444
Early online date24 Dec 2017
DOIs
Publication statusPublished - 7 May 2018

Keywords

  • Isotope dilution
  • Kinetic model
  • Liver
  • phenylalanine
  • Tyrosine

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