NITRIC-OXIDE AND RADIATION ENTERITIS

Objective: To investigate the changes in intestinal nitric oxide (NO) and myeloperoxidase (MPO) concentrations, the rate of endotoxaemia, an d intestinal mucosal structure in rats after irradiation of the abdome n and to find out the effect of N-omega-nitroarginine methyl ester (L- NAME) inhibition NO synthesis. Setting: Medical school, Turkey. Design : Experimental study. Material: 46 Wistar-albino rats. Interventions: In Group I (n = 12), rats underwent abdominal irradiation alone. In Gr oup II (n = 12), they underwent abdominal irradiation and were given L -NAME orally for 3 days before and 3 days after irradiation. In Group III (n = 12), rats had abdominal irradiation and were given L-NAME ora lly for 3 days after irradiation. Group TV (n = 10) were controls and were untreated. The irradiation procedure consisted of a single shot o f 1000 cGy to the abdomen and L-NAME was given 30 mg/kg/ day orally in the drinking water. Main outcome measures: Intestinal mucosal MPO and nitrite, and plasma endotoxin concentrations. Changes in villous heig ht and number were recorded. Results: In groups II and III, MPO and NO 2- concentrations decreased significantly compared with group I. Mucos al integrity was protected in both groups treated with L-NAME (groups II and III) in contrast to the group given irradiation without treatme nt (group I). Conclusion: These results suggest that the NO pathway co ntributes to the inflammatory response of radiation enteritis. Inhibit ion of NO synthesis may have a beneficial effect in the treatment of i nflammation caused by irradiation.