Role of sulphydryl compounds in the defense of rat gastric epithelial cells against oxygen reactive metabolite-induced damage.

This study evaluated the role of endogenous and exogenous sulphydryl compounds in the defense of rat gastric epithelial cells against damage brought about by oxygen reactive metabolites in vitro. Toxic oxygen species were generated by xanthine oxidase in the presence of xanthine. Cell damage was assessed by 51 chromium release assay. Our data confirm that xanthine oxidase, in the presence of xanthine damages cultured rat gastric cells in a dose dependent manner (r = 0.0885, p less than 0.05). Depletion of endogenous thiols by N-ethylmaleimide significantly increases the amount of damage induced by oxygen radicals causing, at the concentration of 0.005 mM, a 60% increase in 51 chromium release (p less than 0.001). The sulphydryl agent cysteamine did not prevent cell damage induced by oxygen reactive metabolites. In conclusion, 1) depletion of endogenous thiols significantly increases the susceptibility of rat gastric epithelial cells to oxygen radical-induced damage; 2) this damage is not prevented by an exogenous agent containing a SH group.