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Liver intracellular L-cysteine concentration is maintained after inhibition of the trans-sulfuration pathway by propargylglycine in rats.

Abstract
To study the fate of L-cysteine and amino acid homeostasis in liver after the inhibition of the trans-sulfuration pathway, rats were treated with propargylglycine (PPG). At 4 h after the administration of PPG, liver cystathionase (EC 4.4.1.1) activity was undetectable, L-cystathionine levels were significantly higher, L-cysteine was unchanged and GSH concentration was significantly lower than values found in livers from control rats injected intraperitoneally with 0.15 M-NaCl. The hepatic levels of amino acids that are intermediates of the urea cycle, L-ornithine, L-citrulline and L-arginine and blood urea were significantly greater. Ura excretion was also higher in PPG-treated rats when compared with control rats. These data suggest a stimulation of ureagenesis in PPG-treated rats. The inhibition of gamma-cystathionase was reflected in the blood levels of amino acids, because the L-methionine: L-cyst(e)ine ratio was significantly higher in PPG-treated rats than in control rats; blood concentration of cystathionine was also greater. Histological examination of liver and kidney showed no changes in PPG-treated rats when compared with controls. The administration of N-acetylcysteine (NAC) to PPG-treated rats reversed the changes in blood urea and in liver GSH. These data suggest that when liver L-cysteine production was impaired by the blockage of the trans-sulfuration pathway, the concentration of this amino acid was maintained mainly by an increase in protein degradation and by a depletion in GSH concentration that may spare L-cysteine.
AuthorsA Triguero, T Barber, C García, I R Puertes, J Sastre, J R Viña
JournalThe British journal of nutrition (Br J Nutr) Vol. 78 Issue 5 Pg. 823-31 (Nov 1997) ISSN: 0007-1145 [Print] ENGLAND
PMID9389904 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References
  • Alkynes
  • Cystathionine
  • propargylglycine
  • Urea
  • Methionine
  • Cystathionine gamma-Lyase
  • Glutathione
  • Cysteine
  • Glycine
  • Acetylcysteine
Topics
  • Acetylcysteine (pharmacology)
  • Alkynes (pharmacology)
  • Animals
  • Cystathionine (blood, metabolism)
  • Cystathionine gamma-Lyase (antagonists & inhibitors)
  • Cysteine (blood, metabolism)
  • Depression, Chemical
  • Glutathione (metabolism)
  • Glycine (analogs & derivatives, pharmacology)
  • Liver (metabolism)
  • Male
  • Methionine (blood)
  • Rats
  • Rats, Wistar
  • Urea (urine)

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