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 karyorr hexis) in the forestomach mucosa was examined in Sprague-Dawley male r ats given a single oral dose of 50 or 150 mg/kg of the gastric carcino gen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) 17 h after the adminis tration of 2 ml of a 3 M NaCl solution. Rats pretreated with NaCl disp layed an incidence of nuclear anomalies approximately 3-fold greater t han the one observed in rats given MNNG alone, and micronucleated cell s accounted to a significant extent for this increase. These findings confirm that NaCl presumably acts as cocarcinogen 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.