Effect of urinary pH on the progression of urinary bladder tumours

Systemic alkalosis has been postulated to enhance tumorigenesis, whereas sy stemic acidosis has been implicated to exert a favourable influence on tumo ur control and regression. In the present study the urinary pH was influenc ed by feeding acid-forming or base-forming diets, and the effect of alkalin e or acid urine on the early and late progression phase of urinary bladder carcinogenicity was investigated in male Wistar rats. Bladder lesions were initiated by N-butyl-N-(4-hydroxybutyl) nitrosamine (0.05% BBN in the drink ing water during 4 weeks) and promoted by sodium bicarbonate (3.4% NaHCO3 i n the diet during 15 or 25 weeks). After short- (15 week) and more long-ter m (25 week) promotion with NaHCO3, groups of 20 rats were fed a diet contai ning the acidifying salt ammoniumchloride (2.1% NH4Cl) or the control diet. All surviving rats were killed after a total study duration of 52 weeks. A dditional control groups were, after initiation, fed diets containing NaHCO 3 and killed after 15 wk or 25 wk of promotion, or at the end of the study. In rats fed diets with added salts, water intake and the amount of urine p roduced were increased and the urinary density was decreased compared to ra ts fed control diet. During NaHCO3 feeding, urinary pH and sodium concentra tion were increased. During NH4Cl feeding, urinary pH was decreased and uri nary chloride and calcium concentrations were increased. Initiation by BBN followed by treatment with NaHCO3 caused a high incidence of papillary/nodu lar hyperplasia. papillomas and carcinomas of the bladder epithelium. These lesions progressed with time or longer duration of NaHCO3 promotion. A tum our protective effect of urinary acidification by NH4Cl was not found. In f act, both acidification and prolonged alkalinization tended to aggravate th e malignancy of bladder carcinomas. (C) 2000 Elsevier r Science Ltd. All ri ghts reserved.