CHANGES IN NITRIC-OXIDE PRODUCTION WITH LESION DEVELOPMENT IN THE GASTRIC-MUCOSA OF RATS WITH WATER IMMERSION RESTRAINT STRESS

In rats with gastric mucosal lesions induced by water immersion restra int (WIR) stress over a 6 h period, increases in the serum and gastric mucosal concentrations of nitrite/nitrate, the breakdown products of NO, occurred viith a drastic increase in inducible NO synthase (iNOS) activity in the gastric mucosa. Pretreatment with aminoguanidine (100 mg/kg), a relatively selective iNOS inhibitor, attenuated not only gas tric mucosal lesion development, but also increases in serum and gastr ic mucosal nitrite/nitrate concentrations with inhibition of increased gastric mucosal iNOS activity in rats with 6 h of WIR stress. A good positive correlation between either serum or gastric mucosal nitrite/n itrate concentration and gastric mucosal iNOS activity in all rats use d (r = 0.741 or 0.842, respectively, p < 0.001) was found. These resul ts suggest that in WIR-stressed rats, an increase in NO production via iNOS in the gastric mucosa could contribute to gastric mucosal lesion development.