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 restraint (WIR) stress over a 6 h period, increases in the serum and gastric mucosal concentrations of nitrite/nitrate, the breakdown products of NO, occurred with 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 gastric mucosal lesion development, but also increases in serum and gastric 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/nitrate concentration and gastric mucosal iNOS activity in all rats used (r = 0.741 or 0.842, respectively, p < 0.001) was found. These results suggest that in WIR-stressed rats, an increase in NO production via iNOS in the gastric mucosa could contribute to gastric mucosal lesion development.