An experimental study on bladder carcinogenesis in dogs by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) and its urinary metabolites

N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) was administered to beagle dogs to examine the urinary metabolites. After extraction and purification of the urine sample, the urinary metabolites were identified by gas-chromatography mass-spectrometry and measured using a gas chromatograph equipped with a thermal energy analyzer (GC-TEA). Five N-nitroso-compounds (N-butyl-N-(3-carboxypropyl)nitrosamine (BCPN), N-butyl-N-(2-hydroxy-3-carboxypropyl)-nitrosamine (BHCPN), N-butyl-N-(carboxymethyl)-nitrosamine (BCMN), N-butyl-N-(2-oxopropyl) nitrosamine (BOPN) and BBN-glucuronide) were detected and identified by comparison with mass spectra of synthetic specimens. In the quantitative analysis by GC-TEA, BCMN greater than BHCPN greater than BCPN were larger part than BOPN and BBN-glucuronide. In early experimental period (0-25 wks) administered BBN (600 mg/day) to two dogs, small tumor was recognized in the urinary bladder of one dog earlier than the other. The former dog excreted larger amounts of BCPN in the urine than the latter. In late experimental period (100 wks approximately) administered BBN (400 mg/day) to five dogs, the dog that was found initial tumor earliest (103 wk) excreted the largest amounts of BCPN in the urine. Therefore, the excretion of BCPN had correlated with the carcinogenesis.