Abstract

The renal clearance of fluoride (CF) was studied in pentobarbital-anesthetized rats. Urine flow rate and chloride clearance, previously thought to be the main determinants of CF, were readily dissociated from CF. Neither the clearance of sodium nor the excretion of potassium correlated consistently with CF. In experiments designed to manipulate urinary pH, viz., the administration of NaHCO3 or NH4Cl, acetazolamide, and mannitol, CF correlated closely with urinary pH. At a urinary pH of 5.0-k96, CF/GFR averaged less than 5%, while at a urinary pH of approximately 7.6, mean CF/GFR exceeded 65%. The data suggest that 35-45% of the filtered fluoride is reabsorbed in the proximal tubule, regardless of the final urinary pH, while in acidosis the majority of fluoride reabsorption occurs in the distal nephron. The results suggest that the tubular reabsorption of fluoride is inversely related to tubular fluid pH. Fluoride reabsorption seems to occur by nonionic diffusion, apparently as hydrogen fluoride. Depending on local pH gradients, it may occur along the entire nephron.

• Related Studies :

  • Fluoride metabolism

    Knowledge of all aspects of fluoride metabolism is essential for comprehending the biological effects of this ion in humans as well as to drive the prevention (and treatment) of fluoride toxicity. Several aspects of fluoride metabolism - including gastric absorption, distribution and renal excretion - are pH-dependent because the coefficient

  • Environmental and physiological factors affecting dental fluorosis

    In addition to differences in fluoride intake and possibly to calcium deficiency or malnutrition, there are several factors which may account for individual differences in the occurrence of dental fluorosis. Disorders in acid-base balance affect the renal handling of fluoride such that, in acidosis, the excretion rate is diminished and,

  • Fluoride pharmacokinetics during acid-base balance changes in man

    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

  • Intake and metabolism of fluoride

    The purpose of this paper is to discuss the major factors that determine the body burden of inorganic fluoride. Fluoride intake 25 or more years ago was determined mainly by measurement of the concentration of the ion in the drinking water supply. This is not necessarily true today because of

  • Plasma and developing enamel fluoride concentrations during chronic acid-base disturbances

    Mild acid-base disturbances were induced in rats for 30 days. These disturbances did not affect % ash of maxillary incisors or % P of the developing enamel from mandibular incisors. Total fluoride intake (food and water) among groups drinking fluoride-free water was constant. Nevertheless, average plasma and developing enamel fluroide

• Related FAN Content :

  • Annapolis: Water Fluoridation Linked to Death of Dialysis Patient

    EVENING CAPITAL (Annapolis, Maryland) November 29, 1979 Fluoride Linked to Death by Mary Ann Kryzankowicz Staff Writer Fluoride poisoning has been definitely linked to the death of a 65-year-old kidney dialysis patient who became ill during a blood cleaning process Nov 11. State Medical Examiner Dr. (illegible) Guard has ruled that Lawrence Blake, 65, of Arundel

  • Factors which increase the risk for skeletal fluorosis

    The risk for developing skeletal fluorosis, and the course the disease will take, is not solely dependent on the dose of fluoride ingested. Indeed, people exposed to similar doses of fluoride may experience markedly different effects. While the wide range in individual response to fluoride is not yet fully understood, the following are some of the factors that are believed to play a role.

  • Nutrient Deficiencies Enhance Fluoride Toxicity

    It has been known since the 1930s that poor nutrition enhances the toxicity of fluoride. As discussed below, nutrient deficiencies have been specifically linked to increased susceptibility to fluoride-induced tooth damage (dental fluorosis), bone damage (osteomalacia), neurotoxicity (reduced intelligence), and mutagenicity. The nutrients of primary importance appear to be calcium,

  • Mayo Clinic: Fluoridation & Bone Disease in Renal Patients

    The available evidence suggests that some patients wtih long-term renal failure are being affected by drinking water with as little as 2 ppm fluoride. The finding of adverse effects in patients drinking water with 2 ppm of fluoride suggests that a few similar cases may be found in patients imbibing 1 ppm, especially if large volumes are consumed, or in heavy tea drinkers. The finding of adverse effects in patients drinking water with 2 ppm of fluoride suggests that a few similar cases may be found in patients imbibing 1 ppm, especially if large volumes are consumed, or in heavy tea drinkers and if fluoride is indeed the cause. It would seem prudent, therefore, to monitor the fluoride intake of patients with renal failure living in high fluoride areas.

  • Kidney Patients Are at Increased Risk of Fluoride Poisoning

    It is well established that individuals with kidney disease are susceptible to suffering bone damage and other ill effects from low levels of fluoride exposure. Kidney patients are at elevated risk because when kidneys are damaged they are unable to efficiently excrete fluoride from the body. As a result, kidney patients