Toxicity, tissue changes, and tumor induction in inbred Swiss mice by methylnitrosamine and -amide compounds.

The toxic and carcinogenic actions of four methylnitrosamine or -amide compounds, given as a single intraperitoneal injection to newborn and adult inbred Swiss mice, were examined. Toxicity was approximately directly proportional to the stability of the three compounds capable of methylating macromolecules in vitro. Methylnitrosourea induced a high incidence of thymic lymphomas in adults and newborns of either sex. Dimethylnitrosamine induced a high incidence of hepatomas in new borns only. These two drugs, as well as methylnitrosourethan and methylnitroso-p-tolylsulfonamide, induced a high inci dence of pulmonary adenomas. Mice given a single sublethal intraperitoneal injection of methylnitrosourea underwent cell depletion of the thymolymphoid and myeloid systems, followed by recovery. These events occurred more rapidly in the myeloid systems than in the thymolymphoid system. These events may represent steps in the genesis of lymphomas induced by methylnitrosourea.