Influence of dose of N-methyl-N-nitrosourea on the induction of urinary bladder cancer in rats.
N-methyl-N-nitrosourea (MNU) was instilled by a urethral catheter into the urinary bladders of female Wistar rats in weekly doses of 0.5 mg for 1, 2, 3 and 4 weeks. At 75 weeks after the initial dose of MNU, the incidences of bladder cancer were 0, 7, 50 and 64% for the total doses of MNU of 0.5, 1.0, 1.5 and 2.0 mg, respectively. Control rats instilled with 0.9% NaCl only for 1--4 weeks did not develop bladder cancer by 75 weeks. Higher doses of MNU of 4.0 and 6.0 mg, given weekly in 0.5 mg amounts for 8 and 12 weeks, respectively, induced a higher incidence (nearly 90%) of urinary bladder cancer in rats at 22--28 weeks. However, it was shown that control rats given 12 weekly installations of solvent only developed a significant number (33%) of bladder cancers by 22--28 weeks.
D000818:Animals; D002295:Carcinoma, Transitional Cell / Q000139:chemically induced*; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D008770:Methylnitrosourea / Q000008:administration & dosage*; D009374:Neoplasms, Experimental / Q000139:chemically induced; D009607:Nitrosourea Compounds / Q000008:administration & dosage*; D051381:Rats; D014521:Urethra; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced*; D014546:Urinary Catheterization
D009607:Nitrosourea Compounds; D008770:Methylnitrosourea