Biomedical subjects
Publications and source records attributed to R H Ophaug.
The urinary excretion of cyclic 3'5'-adenosine monophosphate (cAMP) was measured in rats provided a low fluoride diet (less than 0.5 ppm) and drinking water containing either 0 or 25 ppm of fluoride. The pMole cAMP/microgram creatinine ratio decreased with age but was not influenced by fluoride intake.
We found no significant difference between the means for ionic, bound, and total fluoride concentrations in the plasma of male and female subjects of the same age, living in a community with fluoridated water. When results for the 264 fasting subjects were therefore combined according to age, they indicated that persons over 60 years of age have a significantly higher mean ionic (3.89 mumol/L) and total (6.58 mumol/L) fluoride concentration in plasma than do younger age groups. For younger age groups, means ranged from 2.74 to 3.05 mumol/L for ionic fluoride and from 4.74 to 5.58 mumol/L for total. The bound fluoride concentration was lower in individuals 21 to 30 years of age (1.89 mumol/L) than in older age groups (for whom means ranged from 2.42 to 2.68 mumol/L), but was not significantly different from that of individuals who were younger (2.21 mumol/L). A tendency for the mean ionic fluoride concentration to increase with age was noted, but the concentration was significantly higher than the preceding decade group only in those persons over 60 years of age.
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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.
The adjustments in total fluoride concentration in plasma, bones, liver, and muscle were examined when rats were given a diet of very low fluoride content following a dietary regimen of elevated fluoride intake. The animals received a diet containing 34 ppm of fluoride and water with 50 ppm added fluoride in the 28-day initial period and in the depletion period they were given a diet containing only 0.21 ppm of fluoride and distilled water. The findings indicated a 12-fold increase in the fluoride content of the humeri after 28 days of high-flurodie intake with a greater increment by the epiphyses than by the diaphyses. During 21 days of the depletion period the skeletal fluoride was reduced by only 7.7% indicating a marked retention of fluoride during processes of bone remodeling and growth. The plasma, muscle, and liver total fluoride contents were significantly increased at the end of the period of high-fluoride intake, but these concentrations were found to be restored to base-line levels in 3-7 days of the depletion period. By comparison of the distribution of total fluoride with injected radiofluoride between tissue and plasma waters, it was concluded that muscle and liver contain bound fluoride that does not exchange completely with ionic fluoride.
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The solubility of magnesium in bone mineral from control and magnesium-dificient rats receiving varying fluoride intakes was assessed. Evidence for the existence of a fluoride-related pool of skeletal magnesium possessing a diminished solubility was obtained.
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