CONTRIBUTION OF NO SYNTHASES TO NEUTROPHIL INFILTRATION IN THE GASTRIC-MUCOSAL LESIONS IN RATS WITH WATER IMMERSION RESTRAINT STRESS

A decrease in constitutive NO synthase (cNOS) activity and an increase in inducible NO synthase (iNOS) activity occurred with an increase in myeloperoxidase (MPO) activity, an index of neutrophil infiltration, in the gastric mucosa of rats with water immersion restraint (WIR) str ess. This increase in gastric mucosal MPO activity was enhanced by pre treatment with N-G-monomethyl L-arginine, a non-selective NOS inhibito r, but was prevented with maintenance of gastric mucosal cNOS activity by pretreatment with aminoguanidine, a selective iNOS inhibitor. The MPO activity was negatively correlated with the cNOS activity in all W IR-stressed rats used (r = -0.723). These results suggest that a decre ase in cNOS activity could contribute to an increase in neutrophil inf iltration in the gastric mucosa of WIR-stressed rats. (C) 1998 Federat ion of European Biochemical Societies.