Aromatic amino acids are utilized and protein synthesis is stimulated during amino acid infusion in the ovine fetus

Edward A. Liechty, David Boyle, Helen Moorehead, Larry Auble, Scott Denne

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

The purpose of this study was to determine whether the ovine fetus is capable of increased disposal of an amino acid load; if so, would it respond by increased protein synthesis, amino acid catabolism or both? A further purpose of the study was to determine whether the pathways of aromatic amino acid catabolism are functional in the fetus. Late gestation ovine fetuses of well-nourished ewes received an infusion of Aminosyn PF alone (APF), and Aminosyn PF + glycyl-L-tyrosine (APF+GT) at rates estimated to double the intake of these amino acids. The initial study, using APF, was performed at 126 ± 1.4 d; the APF+GT study was performed at 132 ± 1.7 d (term = 150 d). Phenylalanine and tyrosine kinetics were determined using both stable and radioactive isotopes. Plasma concentrations of most amino acids, but not tyrosine, increased during both studies; tyrosine concentration increased only during the APF+GT study. Phenylalanine rate of appearance and phenylalanine hydroxylation increased during both studies. Tyrosine rate of appearance increased only during the APF+GT study; tyrosine oxidation did not increase during either study. Fetal protein synthesis increased significantly during both studies, producing a significant increase in fetal protein accretion. Fetal proteolysis was unchanged in response to either amino acid infusion. These results indicate that the fetus responds to an acute increase in amino acid supply primarily by increasing protein synthesis and accretion, with a smaller but significant increase in amino acid catabolism also. Both phenylalanine hydroxylation and tyrosine oxidation are active in the fetus, and the fetus is able to increase phenylalanine hydroxylation rapidly in response to increased supply.

Original languageEnglish
Pages (from-to)1161-1166
Number of pages6
JournalJournal of Nutrition
Volume129
Issue number6
StatePublished - 1999

Fingerprint

Aromatic Amino Acids
aromatic compounds
fetus
tyrosine
Sheep
Fetus
protein synthesis
Tyrosine
Phenylalanine
phenylalanine
Amino Acids
sheep
amino acids
amino acid metabolism
hydroxylation
Hydroxylation
Proteins
Fetal Proteins
oxidation
radionuclides

Keywords

  • Amino acid metabolism
  • Mass spectrometry
  • Phenylalanine hydroxylation
  • Sheep
  • Stable isotopes

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Food Science

Cite this

Aromatic amino acids are utilized and protein synthesis is stimulated during amino acid infusion in the ovine fetus. / Liechty, Edward A.; Boyle, David; Moorehead, Helen; Auble, Larry; Denne, Scott.

In: Journal of Nutrition, Vol. 129, No. 6, 1999, p. 1161-1166.

Research output: Contribution to journalArticle

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