The catabolism of urethan in young mice of varying age and strain, and in x-irradiated mice, in relation to urethan carcinogenesis.

Abstract

The rate of catabolism of urethan, which in newborn SWR mice is about 0.1 × the rate found in adults, was shown to increase slowly for the first 10 days after birth and most sharply between the 15th and 20th days. This factor appears to be critical in explaining the greater carcinogenic action of urethan in newborn and young mice. Newborn mice of 4 other strains showed similar low rates of urethan catabolism, though they vary widely in their carcinogenic response to this drug. The rate of urethan catabolism was found to be the same in irradiated and nonirradiated mice, although the former are much more sensitive to urethan leukemogenesis. In these cases, therefore, other factors are responsible for the differences in carcinogenic response to urethan.