Increased frequency of N-methyl-N'-nitro-N-nitrosoguanidine-induced nuclear anomalies in the forestomach of rats pretreated with sodium chloride.

The frequency of nuclear anomalies (micronuclei, pyknosis, and karyorrhexis) in the forestomach mucosa was examined in Sprague-Dawley male rats given a single oral dose of 50 or 150 mg/kg of the gastric carcinogen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) 17 h after the administration of 2 ml of a 3 M NaCl solution. Rats pretreated with NaCl displayed an incidence of nuclear anomalies approximately 3-fold greater than the one observed in rats given MNNG alone, and micronucleated cells accounted to a significant extent for this increase. These findings confirm that NaCl presumably acts as co-carcinogen in the initial phase of gastric carcinogenesis, and suggest that its administration before the carcinogen might increase the sensitivity of short-term tests for the preliminary screening of potential gastric carcinogens.