F344 SHI RATS BEARING TYPE-B CATALASE-1 LOCUS ARE SENSITIVE TO SODIUML-ASCORBATE PROMOTION OF 2-STAGE URINARY-BLADDER CARCINOGENESIS/

Our previous data showed that F344/DuCrj and LEW/Crj rat strains beari ng the type a catalase-1 locus (CS1(a)) are sensitive to the promoting activity of sodium L-ascorbate (Na-AsA) in 2-stage urinary bladder ca rcinogenesis, whereas ODS/Shi and WS/ Shi rat strains bearing the type b catalase-1 locus (CS1(b)) are resistant. In present study, we inves tigated the susceptibility of F344/Shi rats also bearing the CS1 to th e Na-AsA-promoting effects on bladder tumor development. Male rats, 6 weeks old, were given 0.05% N-butyl-N-(4-hydroxybutyl) nitrosamine (BB N) in their drinking water for 4 weeks, then fed either basal diet sup plemented with 5% Na-AsA or no chemicals for 32 weeks. The rats given BBN alone had a few small carcinomas in the urinary bladder. In contra st, animals administered BBN-Na-AsA had many large carcinomas. Adminis tration of Na-AsA was associated with significant elevation of urinary pH and L-ascorbic acid. The results indicate that F344/Shi rats are s ensitive to the promoting effects of Na-AsA on 2-stage urinary bladder carcinogenesis, and thus that the CS1 locus may not influence suscept ibility to promotion. (C) 1998 Wiley-Liss, Inc.