S. Wang et al., HEPATIC EXPORT OF GLUTATHIONE AND UPTAKE OF CONSTITUENT AMINO-ACIDS, GLUTAMATE AND CYSTEINE, IN BROILERS IN-VIVO, Poultry science, 77(10), 1998, pp. 1556-1564
This study was conducted to document the glutathione (GSH) cycle (inte
rorgan circulation of GSH) in broilers in vivo. Two experiments were c
onducted on 36 anesthetized male, broilers (n = 6 per treatment) impla
nted with cannulae in. the carotid artery, hepatic portal, and hepatic
veins. Plasma GSH, glutamate, cysteine, cystine and cysteinylglycine
levels in each vessel were monitored following a bolus injection [Expe
riment (Exp.) 1] or 30 min continuous infusion (Exp. 2) of GSH, or a g
amma-glutamyltranspeptidase inhibitor (AT125) into the hepatic portal
vein. Controls received saline alone. The GSH and AT125 treatments wer
e used to determine the effect of increasing the prehepatic GSH bad an
d of inhibiting systemic GSH degradation, respectively, on the GSH cyc
le. Hepatic export of GSH was clearly evident in all three treatment g
roups in both experiments (Exp.). The GSH and AT125 treatments raised
amino acid levels in some or all of the vessels, whereas cysteinylglyc
ine was elevated by AT125 and depressed by the GSH treatment compared
to Controls. Hepatic uptake of glutamate, cysteine, and/or cystine was
observed in Controls and GSH-treated birds, but not in birds given AT
125 (Exp. 2). Neither hepatic export nor uptake of cysteinylglycine wa
s observed in any treatment group. The results clearly demonstrate the
ability of the avian Liver to export GSH into the general circulation
despite alterations that might arise from changes in extra-hepatic ab
ility to utilize GSH or its constituent amino acids.