Abstract

High exposures to fluoride (F-) may occur in environments rich in F- from natural or industrial sources and from misuse of F–containing dental care products, particularly by children. Both acute and chronic exposures to elevated levels of F- have negative effects on several calcium-dependent processes, including kidney glomerular and tubular function. We examined the effect of chronic F- ingestion on ATP-dependent 45Ca uptake by rat kidney membrane vesicles to characterize the mechanism by which high F- alters Ca++ transport in the kidney. Twenty weanling female Sprague-Dawley rats were raised on low-F- (0.9 mg/L), semi-purified diet with a Ca++ concentration of 400 mg/100g diet. Rats were divided into four groups and were fed ad libitum deionized water containing F- at 0, 10, 50, or 150 mg/L added as NaF for 6 wk. This consumption produced plasma F- levels of <0.4, 2, 7, or 35 micromol/L, respectively. ATP-dependent 45Ca uptake was significantly lower in the 150 mg F-/L exposure group than in the 0 mg F-/L controls (P < 0.05). Studies with thapsigargin, a specific inhibitor of the endoplasmic reticulum Ca++-pump, showed that the lower uptake was associated with significantly lower activities of both the plasma membrane Ca++-pump (P < 0.05, 150 mg F-/L group versus control) and endoplasmic reticulum Ca++-pump (P < 0.05 for both the 50 and 150 mg F-/L groups versus control). Slot blot analysis of kidney homogenates with specific Ca++-pump antibodies showed less (P < 0.05) endoplasmic reticulum Ca++-pump protein and plasma membrane Ca++-pump protein in all treatment groups than controls. Both Ca++-pumps are transport molecules of great importance in the regulation of Ca++ homeostasis. Our study suggests that chronic, high F- ingestion producing high plasma F- levels may occur in humans and may affect Ca++ homeostasis by increasing the turnover or breakdown or decreasing the expression of plasma membrane and endoplasmic reticulum Ca++-pump proteins.

*Abstract online at https://europepmc.org/article/MED/10356089#abstract

• Related Studies :

  • Inorganic fluoride kinetics and renal tubular function after sevoflurane anesthesia in chronic renal failure patients receiving hemodialysis

    Although sevoflurane is used in clinical anesthesia, its effects on renal function and inorganic fluoride (F-) kinetics in patients with chronic renal failure (CRF) have not been determined. We investigated F- kinetics and renal tubular function in sevoflurane anesthesia in CRF patients having hemodialysis. Five patients dialyzed and five with

  • Prevention of brick tea fluorosis in rats with low-fluoride brick tea on laboratory observation

    To test whether low-fluoride brick tea can prevent the occurrence of fluorosis, rats had access only to a specially prepared low-fluoride brick tea for 1 year. The daily fluoride intake, fluoride metabolism, tissue distribution and development of tooth fluorosis were observed at 4-monthly intervals, at the end of months 4,

  • Fluoride in drinking water and diet: the causative factor of chronic kidney diseases in the North Central Province of Sri Lanka

    A significant number of people in the North Central Province of Sri Lanka suffer from chronic kidney diseases (CKD), and the author revisits existing literature related to CKD to find its causative factor. There is a direct connection between high fluoride levels in drinking water and kidney disease, and there

  • Studies on the DNA and RNA contents of heart, liver and kidney of rats with chronic fluorosis

    17 rats with chronic fluorosis induced by prolonged drinking of water containing 50 ppm fluorine and 17 rats drinking low-fluorine water served as control were used to study the DNA and RNA contents of heart, liver and kidney. The findings suggest that excessive accumulation of fluorine can suppress the synthesis

  • Endemic fluorosis in the Madras presidency

    1. Ten cases of chronic fluorine intoxication have been investigated, clinically, radiologically, and, as regards blood and urine, biochemically. 2. The clinical picture is described and relates chiefly to disabilities caused by calcification of ligaments, tendons and fasciae, the formation of osteophytic outgrowths of bone and the nervous effects of mechanical

• Related FAN Content :

  • Kidney: A potential target for fluoride toxicity

    The kidneys are the organ responsible for clearing fluoride from the body. In the process of doing so, the kidneys are exposed to concentrations of fluoride that exceed, by a factor of 50, the concentration of fluoride in human blood. As such, the kidney have long been considered a potential

  • Fluoridation of drinking water and chronic kidney disease: Absence of evidence is not evidence of absence

    A fairly substantial body of research indicates that patients with chronic renal insufficiency are at an increased risk of chronic fluoride toxicity. Patients with reduced glomerular filtration rates have a decreased ability to excrete fluoride in the urine. These patients may develop skeletal fluorosis even at 1 ppm fluoride in the drinking water.

  • Fluoride as a Cause of Kidney Disease in Humans

    Because the kidney is exposed to higher concentrations of fluoride than all other soft tissues (with the exception of the pineal gland), there is concern that excess fluoride exposure may contribute to kidney disease - thus initiating a "vicious cycle" where the damaged kidneys increase the accumulation of fluoride, causing

  • Fluoride & Kidney Stones

    It has long been suspected that fluoride may contribute to the formation of kidney stones. This suspicion has recently gained support from a study of an American man with skeletal fluorosis. According to the authors: "A new, important, medical problem (that seemed temporally related to cessation of fluoride exposure and subsequent negative calcium

  • Fluoride Gels & Kidney Function

    Scientists have found that the application of "Fluoride Gels" at the dental office causes very high spikes in the blood fluoride level. The high spikes in blood fluoride levels are a result of three factors: the high concentration of fluoride in the gel (= 12.3 mg of fluoride in each