Hepatic glutathione degradation within the sinusoids of guinea pig livers shows a periportal localization of gamma-glutamyl transferase activity.
In utilizing intact perfused guinea pig livers a probable periportal localization of gamma-glutamyl transferase (GGT) activity was apparent. Untreated livers perfused from the portal to hepatic vein had a significantly greater glutathione efflux than the same livers perfused from the hepatic to portal vein. Switching the perfusion direction also saw a significant rise in the cysteinylglycine efflux. It was apparent from the results that the efflux of glutathione degradation products from the guinea pig livers was significantly greater than those of the intact tripeptide. However, with maximal GGT inhibition glutathione accounted for 90% of the glutathione-related thiols exported from the liver with cysteine accounting for the remaining 10%. Therefore, glutathione exported from hepatocytes may act as a means of transporting its constituent amino acids. The periportal localization of GGT activity ensures that the more susceptible perivenous region faces the greatest concentration of glutathione degradation products.
Department of Clinical Pharmacology and Toxicology, St. Vincent's Hospital, Darlinghurst, Sydney, Australia.
N A
NA
Shackel
H
H
Speisky
D N
DN
Wade
D000818:Animals; D004151:Dipeptides / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D005723:gamma-Glutamyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism*
D004151:Dipeptides; C028505:cysteinylglycine; D005723:gamma-Glutamyltransferase; D005978:Glutathione