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  • Secretion  (1)
  • fluoride  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 54 (1994), S. 421-425 
    ISSN: 1432-0827
    Keywords: Metabolism ; Secretion ; Balance ; Osteoporosis ; Magnesium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract This 30-day balance study with weanling rats was designed to determine the effects of plasma fluoride and dietary calcium concentration and their interaction on the absorption, balance, and tissue concentrations of fluoride. The three major groups differed according to the total exposure and plasma concentrations of fluoride. One group received fluoride only in the diet and the other two received additional fluoride by continuous infusion from miniosmotic pumps implanted S.C. Each group was divided into two subgroups with dietary calcium concentrations of 0.4% or 1.4%. Fluoride intake with the diet did not differ among the groups. Fecal fluoride excretion was directly related to plasma fluoride concentration. The absorption and balance of dietary fluoride were inversely related to plasma fluoride concentration. These effects were greatest in the groups fed the 1.4% calcium diet. The interactions of plasma fluoride and dietary calcium on these variables were highly significant (P〈0.0001). The balance of dietary fluoride was negative in the four groups that received additional fluoride by infusion. In the two groups that received fluoride only in the diet, the plasma and bone fluoride concentrations were 41% and 59% lower, respectively, in the 1.4% dietary calcium group. The findings indicate that net fluoride secretion into the GI tract can occur when plasma fluoride concentrations and calcium intake are elevated. They suggest that elevated plasma fluoride levels and calcium intake are factors that may diminish the effect of oral fluoride treatment in osteoporotic patients.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 18 (1980), S. 189-194 
    ISSN: 1432-1041
    Keywords: fluoride ; renal clearance ; urinary pH ; fluoride kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Five healthy subjects were each given fluoride 3.0 mg (F) as sodium fluoride tablets on two occasions — during production of acid urine, induced by giving NH4Cl, and during production of alkaline urine obtained by giving NaHCO3. Frequent plasma and urine samples were taken up to 12 h and were analyzed with a F− sensitive electrode. Control experiments without F administrations were also performed to permit calculation of net F concentration in plasma and urine. The urine F excretion was lower during acid than alkaline diuresis. Pharmacokinetic analysis of the net plasma F concentrations showed that the apparent plasma half-life of F was longer when urine was acid (4.3±0.6 h: SD; n=5) than when it was alkaline (2.4±0.4 h). This could be explained by changes in the renal clearance of F, which was always lower with an acid (61.5±8.1 ml/min) than an alkaline (97.8±10.4 ml/min) urine. The apparent extra-renal clearance, which mainly represents clearance to the bone-pool, was also significantly higher during production of alkaline (109.2±20.2 ml/min) than of acid (86.3±21.3 ml/min) urine. It is suggested, that increased reabsorption of non-ionic hydrogen fluoride (HF) is responsible for the decreased renal clearance during acidic conditions.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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