Induction of gastric tumors in BD-VI rats by single application of N-methyl-N'-nitro-N-nitrosoguanidine in dimethylsulfoxide (DMSO).

The oral acute LD50 of N-Methyl-N'-Nitro-N-Nitrosoguanidine (MNNG) in a 10% aqueous solution of dimethylsulfoxide (DMSO) amounted to approximately 90 mg/kg. After single oral application of 50 mg/kg (group I), 75 mg/kg (group II) and 100 mg/kg (group III) of MNNG in a 10% aqueous solution of DMSO, generalized papillomatoses of the forestomach were found in all BD-VI rats after a test period of 500 days. Squamous cell carcinomas could be detected in 7/24 (21%) rats in group I, in 12/26 (46%) in group II and in 7/23 (30%) in group III). Benign adenomatous dysplasia of the glandular stomach was diagnosed in 2 rats (8%) of group I, in 1 animal (4%) of group II and in 12 rats (52%) of group III. Adenocarcinomas of the glandular stomach were induced in 1 animal (4%) of both group I and II and in 8 rats (35%) of group III. 20--30% of the animals treated with MNNG also showed degenerative cystic alterations in the liver with bile-duct proliferation.