Binding of labeled N-methyl N-nitrosourea to macromolecules of squamous and glandular stomach of rats.

The binding of labeled N-methyl-N-nitrosourea (3H-MNU) to macromolecules of squamous and glandular stomach of rats, that were either pretreated with N-methyl-N-nitrosourea (MNU) for different periods or without pretreatment, is studied. The results showed no significant difference in the binding of labeled carcinogen to DNA and RNA of the two portions of stomach. However, a significant increase was noted in the incorporated 3H-MNU in proteins of glandular stomach with or without pretreatment with MNU. From these studies it is implied that carcinogenic effect of MNU may be through interaction with some other molecule(s) rather than with nucleic acids and/or proteins.