Uracil-induced urolithiasis in the urinary bladder of rats is irritation-dependent

The correlation between urolithiasis due to uracil administration and epithelial proliferation in the urinary bladder was investigated in male F344 rats. Animals, 6 weeks old at the start, which ingested 3% uracil alone in the diet for 4 weeks developed urolithiasis and papillomatosis of the urinary bladder, whereas addition of NaCl, particularly at high concentration (10%), to the 3% uracil in the diet blocked production of both. In contrast, NaHCO3 was without influence on either calculi or proliferative changes. These results indicate that uracil-induced epithelial proliferation is due to direct mechanical irritation by calculi, and not to any chemical stimulus presented by uracil itself.