Studies on the putative role of γ-glutamyl transpeptidase in intestinal transport of amino acids in Atlantic salmon

J. G. Bell, Randal Buddington, M. J. Walton, C. B. Cowey

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The γ-glutamyl cycle is considered to function in the membrane transport of amino acids, particularly glutamine and cysteine. When groups of Atlantic salmon were fed either a control diet containing 45% crude protein or an amino acid diet (of similar overall amino acid composition but containing elevated levels of glutamine and cysteine) for 16 weeks, weight gains were significantly greater in the former group than in those given the amino acid diet. There were no significant differences between treatments in γ-glutamyl transpeptidase (GT) activity in the proximal intestine; in distal intestine there was significantly more activity in control fish. Mean levels of GSH were higher in tissues (pyloric caeca, distal intestine and kidney) of amino acid diet fish than in those of control fish. Glutamine was less effective as a γ-glutamyl acceptor than several other amino acids when tested with salmon caecal GT. There were no morphological adaptations to the two feeds. Nutrient uptake studies showed an increased uptake of glutamine, but decreased uptakes of proline and methionine in proximal intestine of salmon fed amino acid diet. Much the greater part of the glutamine uptake, even at high concentrations was shown to be by Na+ dependent processes. There is no evidence that GT itself is Na+ dependent. The results do not support the view that the γ-glutamyl cycle and GT in particular are involved in the transport of amino acids in the intestine and are discussed in this context.

Original languageEnglish (US)
Pages (from-to)161-169
Number of pages9
JournalJournal of Comparative Physiology B: Biochemical, Systemic and Environmental Physiology
Volume157
Issue number2
DOIs
StatePublished - Jan 1 1987

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Salmo salar
gamma-glutamyltransferase
gamma-Glutamyltransferase
amino acid
glutamine
Amino Acids
Nutrition
Glutamine
amino acids
intestines
Intestines
diet
Diet
Fish
Fishes
Salmon
uptake mechanisms
salmon
cysteine
Cysteine

All Science Journal Classification (ASJC) codes

  • Physiology
  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry
  • Animal Science and Zoology
  • Endocrinology

Cite this

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title = "Studies on the putative role of γ-glutamyl transpeptidase in intestinal transport of amino acids in Atlantic salmon",
abstract = "The γ-glutamyl cycle is considered to function in the membrane transport of amino acids, particularly glutamine and cysteine. When groups of Atlantic salmon were fed either a control diet containing 45{\%} crude protein or an amino acid diet (of similar overall amino acid composition but containing elevated levels of glutamine and cysteine) for 16 weeks, weight gains were significantly greater in the former group than in those given the amino acid diet. There were no significant differences between treatments in γ-glutamyl transpeptidase (GT) activity in the proximal intestine; in distal intestine there was significantly more activity in control fish. Mean levels of GSH were higher in tissues (pyloric caeca, distal intestine and kidney) of amino acid diet fish than in those of control fish. Glutamine was less effective as a γ-glutamyl acceptor than several other amino acids when tested with salmon caecal GT. There were no morphological adaptations to the two feeds. Nutrient uptake studies showed an increased uptake of glutamine, but decreased uptakes of proline and methionine in proximal intestine of salmon fed amino acid diet. Much the greater part of the glutamine uptake, even at high concentrations was shown to be by Na+ dependent processes. There is no evidence that GT itself is Na+ dependent. The results do not support the view that the γ-glutamyl cycle and GT in particular are involved in the transport of amino acids in the intestine and are discussed in this context.",
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AU - Buddington, Randal

AU - Walton, M. J.

AU - Cowey, C. B.

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