title: Glutathione replenishment capacity is lower in isolated perivenous than in periportal hepatocytes.
abstract: The zonal distribution of GSH metabolism was investigated by comparing hepatocytes obtained from the periportal (zone 1) or perivenous (zone 3) region by digitonin/collagenase perfusion. Freshly isolated periportal and perivenous cells had similar viability (dye exclusion, lactate dehydrogenase leakage and ATP content) and GSH content (2.4 and 2.7 mumol/g respectively). During incubation, periportal cells slowly accumulated GSH (0.35 mumol/h per g), whereas in perivenous cells a decrease occurred (-0.14 mumol/h per g). Also, in the presence of either L-methionine or L-cysteine (0.5 mM) periportal hepatocytes accumulated GSH much faster (3.5 mumol/h per g) than did perivenous cells (1.9 mumol/h per g). These periportal-perivenous differences were also found in cells from fasted rats. Efflux of GSH was faster from perivenous cells than from periportal cells, but this difference only explained 10-20% of the periportal-perivenous difference in accumulation. Furthermore, periportal cells accumulated GSH to a plateau 26-40% higher than in perivenous cells. There was no significant difference in gamma-glutamylcysteine synthetase or glutathione synthetase activity between the periportal and perivenous cell preparations. The periportal-perivenous difference in GSH accumulation was unaffected by inhibition of gamma-glutamyl transpeptidase or by 5 mM-glutamate or -glutamine, but was slightly diminished by 2 mM-L-methionine. This suggests differences between periportal and perivenous cells in their metabolism and/or transport of (sulphur) amino acids. Our results suggest that a lower GSH replenishment capacity of the hepatocytes from the perivenous region may contribute to the greater vulnerability of this region to xenobiotic damage.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002469:Cell Separation; D005721:Glutamate-Cysteine Ligase / Q000378:metabolism; D005971:Glutamates / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism*; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008715:Methionine / Q000494:pharmacology; D051381:Rats; D014018:Tissue Distribution; D005723:gamma-Glutamyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000596:Amino Acids; D005971:Glutamates; D008715:Methionine; D005723:gamma-Glutamyltransferase; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione; C018830:anthglutin