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Department of Biochemistry, University of Minnesota, Medical School, Minneapolis, Minnesota 55455
To investigate the effect of fluoride on the mobilization of skeletal magnesium and on kidney calcification during magnesium depletion, male Holtzman rats were fed a magnesium-sufficient diet (400 ppm of magnesium) and drinking water containing either 0, 50 or 100 ppm of fluoride for a 20-day period prior to the initiation of magnesium deficiency. The high fluoride regimen resulted in a 100-fold increase in the fluoride content of the skeleton. On day 20 magnesium depletion was initiated by feeding the animals a diet containing 12 ppm of magnesium. Over a 4-week period of magnesium deprivation, a 26% decrease of the total magnesium in the humeri was observed. Fluoride exerted a significant effect in retarding the mobilization of skeletal magnesium. Four weeks of magnesium deficiency was associated with a decreased rate of skeletal mineral accretion and with an increase in the kidney calcium content. The decreased rate of mineral accretion was accentuated by the administration of fluoride during the deficiency state. While fluoride exerted an initial protective effect on calcinosis of the kidneys, the overall effect of the administration of fluoride during magnesium deficiency was to promote calcification of the kidneys rather than to prevent it.
KEY WORDS: deficiency magnesium bone fluoride
1 This investigation was supported by Public Health Service Research Grant No. DE-01850 from the National Institute of Dental Research.
Manuscript received 22 October 1975.