RESUMO
Salt/NaCl has been reported to induce necrosis in gastric mucosal cells, however, the mechanisms for gastric injury by salt are not clarified. In this study, we elucidated whether salt is an oxidative stress inducer via mitochondrial injury on rat gastric epithelial cells (RGM-1) in 300, 450, 650 and 1000 mM of NaCl-contained medium. To clarify whether salt-induced reactive oxygen species (ROS) is derived from mitochondria, we also investigated a salt-induced ROS production in manganese superoxide dismutase overexpressing cells (RGM-MnSOD). MnSOD is a specific scavenger for superoxide anion produced from mitochondria. The results showed that cellular injuries in RGM-MnSOD were significantly less severe than that in normal RGM-1. The electron paramagnetic resonance (EPR) studies also provided an evidence that the salt-derived superoxide production in RGM-MnSOD was less than that in normal RGM-1. These results indicated that salt is not merely a necrotizing factor for gastric epithelial cells, but also an oxidative stress inducer.