Effects of growth factors on acid-induced damage to rat gastric epithelial cells

We previously established a model of cell damage induced by an acidified medium in the rat gastric epithelial cell line RGM1. Treatment of the cells with epidermal growth faster (EGF, 1-10 ng/ml) for 4 h prevented acid-induced cell damage in a concentration-dependent manner. In contrast, basic fibroblast growth factor (1-10 ng/ml) and platelet-derived growth factor BE (1-10 ng/ml) had no effect on cell damage. EGF did not affect DNA synthesis by the cells for 4 h. Pretreatment of the cells with cycloheximide (10 mu g/ml) for 1.5 h before EGF treatment significantly attenuated the cytoprotective effect of EGF by > 50%. Replacement of Na+ with K+ in the acidified medium totally abolished the effect of EGF. Go-incubation with amiloride (1 mM) had no influence on the protective effect of EGF. These results indicate that the cytoprotective effect of EGF appears to involve both the activation of amiloride-resistant Na+/H+ exchangers and the synthesis of a new protein related to Na+/H+ exchangers.