Susceptibility of cultured rat hepatocytes to oxidative stress by peroxides and iron. The extracellular matrix affects the toxicity of tert-butyl hydroperoxide

The aim of this study was to set up an in vitro model for studying the impo rtance of ail altered extra-cellular matrix composition and its importance for the resistance to oxidative stress, in hepatocytes from normal and iron loaded rats. Primary cultures of hepatocytes from iron loaded and normal rats were plate d on a laminin rich extracellular matrix or on collagen type I, and incubat ed with tert-butyl hydroperoxide (TBH), Malon dialdehyde (MDA) and the acti vities of lactate dehydrogenase (LDH) in cell culture medium were analyzed. The protein synthesis, the concentrations of glutathione and the expressio n of manganese-superoxide dismutase and ferritin genes were measured. All hepatocytes contained lower concentrations of glutathione when plated o n collagen than on EHS. Ferritin H and Mn-SOD gene expression showed no dif ference. The rate of lipid peroxidation in iron loaded hepatocytes exposed to TBH was higher on collagen than in those plated on EHS (0.95 +/- 0.28 mu M MDA vs. 1.62 +/- 0.22 mu M MDA, p < 0.05). Iron loaded cells were in gen eral more susceptible to TBH than were normal hepatocytes (MDA, LDH, protei n synthesis and glutathione content). Lipid peroxidation could be prevented by adding desferrioxamine. In conclusion, we show that the combination of iron overload and collagen m atrix in rat hepatocytes leads to an increased susceptibility to oxidative stress. These findings may be of interest for the further studies on effect s of iron overload and the altered matrix composition in liver fibrosis. (C ) 1999 Elsevier Science Ltd. All rights reserved.