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
The expertise of A. Graham Calder and Susan Anderson for the
various stable isotope analyses is gratefully recognised. Celine
Germaine performed the SDH measurements from the tissue
samples as part of a student placement from AgroParisTech,
This study was funded as part of the core grant provided to
the Rowett Institute of Nutrition and Health, University of
Aberdeen and Biomathematics and Statistics Scotland by Rural
and Environment Science and Analytical Services, part of the
Scottish Government. Hoskin was a recipient of a FoRST (NZ)
award to study abroad.
The authors’ contributions were as follows: S. O. H. and G. E. L.
were responsible for study concept and design. S. O. H., G. E. L.
and D. M. B. were responsible for data collection and collation.
G. E. L. and G. H. were responsible for data analysis and statistical
matters. S. O. H., G. E. L. and G. H. were responsible for the
first draft and critical revision of the manuscript for important
The authors declare that there are no conflicts of interest
- endotoxin lipopolysaccharide
- amino acids
- irreversible loss rate
- serine-threonine dehydratase
- acute-phase proteins
- porcine model
- septic rats