Effect of oxygen concentration on the expression of glutathione S-transferase activity in periportal and perivenous rat hepatocyte cultures

Cultures of perivenous (PV) and periportal (PP) hepatocytes could provide s uitable in vitro models for studying the zone-specific hepatotoxic potentia l of xenobiotics. However, it is not known whether cultured PP and PV hepat ocytes keep their phenotypes when the microcirculation of the liver changes . This question has been studied by culturing rat hepatocytes at 13 and 4% (v/v) O-2, respectively, mimicking the acinar oxygen gradient. PP and PV ad ult rat hepatocytes were isolated by digitonin-collagenase in situ perfusio n and cultured on plastic Falcon(R) and gas-permeable Petriperm(R) dishes i n Williams' E medium and kept at 13 and 4% (v/v) O-2, respectively. Culture s at 20% (v/v) O-2 on plastic dishes served as a control. Two types of cult ures were studied, namely conventional cultures either unsupplemented or su pplemented with 30 mm pyruvate. The activities of glutamine synthetase (GS) and glutathione S-transferase (GST) were measured in freshly isolated PP a nd PV hepatocytes and all cultures. The heterogeneous expression of GS (PV > PP), observed in freshly isolated hepatocytes, was kept for at least 4 da ys in culture. Total, Mu and Alpha class GST activities were predominantly expressed in PV freshly isolated cells. However, no beneficial effect could be observed in culture by exposing the cells to their specific in vivo oxy gen concentration. The best maintenance of GST PV predominance in culture w as observed in Petriperm dishes at 20% (v/v) O-2, as well in pyruvate-suppl emented as unsupplemented cultures. PV GST predominance was thus kept in pa rticular when the highest oxygen concentration was used and made available to the cells through the gas-permeable membranes. The results on GS PV pred ominance support these findings. (C) 2001 Elsevier Science Ltd. All rights reserved.