Influences of strain and diet on the promoting effects of sodium L-ascorbate in two-stage urinary bladder carcinogenesis in rats.

The influences of strain and diet on the promoting effects of sodium L-ascorbate (SA) on two-stage urinary bladder carcinogenesis was investigated in male F344 and Lewis rats. Two kinds of commercial basal diets, Oriental MF and Clea CA-1, were used. Rats were given 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine in their drinking water for 4 weeks and then basal diet with 5% SA or without SA for 32 weeks. Treatment with SA increased the induction of neoplastic lesions of the urinary bladder in rats initiated by 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine. The promoting effect of SA for urinary bladder carcinogenesis was: F344 strain-Oriental MF diet greater than Lewis strain-Clea CA-1 diet greater than F344 strain-Clea CA-1 diet = Lewis stain-Oriental MF diet. In both strains or with both diets, SA-treatment increased the urinary pH and the concentrations of sodium ion and total ascorbic acid. These results demonstrate that strain and diet strongly influence susceptibility to the SA-promoting effects in rat urinary bladder carcinogenesis.