Abstract: To study the difference between high dose sodium-chloride diet associate with high dose N-methyl-N'-nitro-N-nitrosoguanidine （MNNG） gavage or low dose MNNG in drinking water in inducing gastric carcinomas in rats. Sixty-six male 6-week-old Wistar rats were divide into 3 groups. Group 1 rats were given MNNG in drinking water at a concentration of 100 mg/L for 17 weeks and were simultaneously fed a diet supplemented with 8% NaCl for 20 weeks. Group 2 rats were initially given MNNG （200 mg/kg b. w. ） by gavage at days 0 and 14 as well as saturated sodium chloride solution （S-NaCl,1 ml per rat） every 3 days during first 3 weeks （six times）, and then treat with high dose of sodium-chloride diet for 17 weeks. Then these two groups of rats were treated with normal diet for 15 weeks. Group 3 rats were fed on normal diet for 35 weeks. At week 20，ten rats of group 1 were killed and at the end of week 35 all surviving animals were killed. All the specimens were histopathologically investigated. The result showed that the incidence of glandular stomach adenocarcinoma in group 1 was 20% in week 20 and in week 35 was 90%. The incidence of forestomach cancer in group 2 was 68.4%. These data indicated that the method of high dose sodium-chloride diet associate with low dose MNNG in drinking water is more effective in inducing glandular stomach adenocarcinoma.

Key words: MNNG, Gastric carcinoma, Model, Rat