RELATIONSHIP BETWEEN CONSTITUTIVE NITRIC-OXIDE SYNTHASE ACTIVITY AND MUCUS LEVEL IN THE GASTRIC-MUCOSA OF RATS WITH STRESS

A decrease in constitutive nitric oxide synthase (cNOS) activity occur red with decreases in hexosamine (an index of mucus synthesis) and adh erent mucus (an index of mucus secretion) concentrations in the gastri c mucosa of rats with water immersion restraint (WIR) stress. The decr eases in gastric mucosal hexosamine and adherent mucus concentrations were enhanced with a further decrease in gastric mucosal cNOS activity by pretreatment with N-G-monomethyl L-arginine, a non-selective NOS i nhibitor, but were prevented with maintenance of the gastric mucosal c NOS activity by pretreatment with aminoguanidine, a selective inducibl e NO synthase inhibitor. In all WIR-stressed rats used in this study, gastric mucosal cNOS activity was well correlated with either gastric mucosal hexosamine or adherent mucus concentration (r = 0.717 or 0.739 , respectively). These results indicate that in the gastric mucosa of WIR-stressed rats, a decrease in cNOS activity is closely related to a decrease in mucus level due to impairment of its synthesis and secret ion. (C) 1998 The Italian Pharmacological Society.