Effect of dose of sodium saccharin on the induction of rat urinary bladder proliferation.

The effect of sodium saccharin fed to male F344 rats at levels of 5.0, 2.5, 1.0, 0.5, and 0.1% of the diet for 10 weeks was evaluated by autoradiography and scanning electron microscopy. A dose response was evident with both techniques. The labeling index was statistically significantly elevated at all doses above 0.1%. As observed by scanning electron microscopy, the number of foci containing ropy microridges or uniform microvilli was elevated at doses of 1.0, 2.5, and 5.0% of the diet, and pleomorphic microvilli were observed at the two highest doses.