Role of Skeleton and Kidney in Fluoride Absorption in Rat

Summary Two studies were conducted in an attempt to learn more concerning the effect of bilateral nephrectomy and previous exposure to fluoride upon rate of fluoride absorption in the rat. The first study was conducted in weanling animals having no previous exposure to fluoride and indicated that bilateral nephrectomy significantly decreased the rate of fluoride absorption by 41.9% during the first 2 hours after fluoride administration and by 41.7% 4 hours thereafter. In the second study, this effect was substantiated using animals exposed to 2 different levels of fluoride. Previous exposure to 125 mg of fluoride decreased the rate of fluoride absorption by 21.9% and when the animals were in addition nephrectomized, a further decrease of 13.7% was noted. After exposure to 250 mg of fluoride, the rate of fluoride absorption was decreased by a similar value of 21.9%. Nephrectomy further decreased the rate of fluoride absorption and the combination of previous exposure and nephrectomy decreased the rate of fluoride absorption by more than 65%. These data suggest that when kidney function becomes impaired the body responds by decreasing the rate of fluoride absorption.