Promoting effects of unilateral ureteric ligation on two-stage urinary bladder carcinogenesis in rats

The effect of ligation of the left ureter on the development of lesions in the urinary bladder were investigated in male F344 rats treated with 0.05% N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) for 2 weeks followed by 0.002% N-ethyl-N-(4-hydroxybutyl)nitrosamine (EHBN) for 10 or 22 weeks. The lesions of the urinary bladder found in weeks 12 and 24 in rats treated with BBN and EHBN were preneoplastic papillary or nodular hyperplasia (PN hyperplasia), papilloma and cancer. The incidences and numbers of these lesions per 10 cm of basement membrane of urinary bladder were increased significantly by ureteric ligation. Treatment with BBN or EHBN only induced no remarkable change and thus the doses used were subcarcinogenic in the conditions used. The results show that unilateral ureteric ligation enhanced two-stage bladder carcinogenesis.