OXYGEN METABOLITES STIMULATE MUCOUS GLYCOPROTEIN-SECRETION FROM CULTURED RAT GASTRIC MUCOUS CELLS

The aims of this study were to investigate the interaction between oxygen radicals and mucus secretion from cultured rat gastric mucous cells, and to assess the role of prostaglandin production in the modulation of mucus secretion in vitro. Xanthine oxidase in the presence of hypoxanthine caused a dose-dependent increase of mucus secretion, as assessed by release of [H-3]glucosamine from prelabeled cells, whereas xanthine oxidase or hypoxanthine alone did not. Xanthine oxidase (10 mU/ml) increased release of [H-3]glucosamine by 57 +/- 6% compared with control values (P < 0.001). Catalase (3,000 U/ml) inhibited xanthine oxidase-induced mucus secretion by 69 +/- 9% (P < 0.01), whereas superoxide dismutase did not. Pretreatment with deferoxamine, an inhibitor of hydroxyl radical generation through chelating ferric ion, diminished oxygen radical-induced mucus release to control values. Xanthine oxidase dose dependently stimulated prostaglandin E2 (PGE2) production, which was blocked by catalase but not by superoxide dismutase. However, oxygen radical stimulation of mucus secretion was not inhibited by the addition of indomethacin. Moreover, PGE2, exogenously administered, did not significantly accelerate mucus secretion. Stimulation of mucus secretion by oxygen radicals was not accompanied by increased Cr-51 release or by leakage of intracellular lactate dehydrogenase. These results suggest that oxygen species, particularly hydroxyl radical, stimulate mucous glycoprotein secretion from cultured rat gastric mucous cells. However, it seems unlikely that prostaglandin production mediates the oxygen species-induced stimulation of mucus secretion.