Fluoride ion toxicity in human kidney collecting duct cells

Several halogenated anesthetics induce a urinary concentrating defect, partly related to fluoride ion toxicity in collecting duct cells. The aim of this study was to investigate the effects of fluoride ion in human kidney cells. Immortalized human collecting duct cells were used. In a first set of experiments, the toxicity threshold concentration was determined by exposing cell cultures for 24 h to increasing concentrations of fluoride ion in the medium: 0, 1, 5, and 10 mM. The second set of experiments was a time- effect study in which cells were exposed to 5 mM fluoride for 2, 6, and 24 h. Assessment of toxicity was based on several endpoints: cell number, protein content, (3)H-leucine incorporation in newly synthesized proteins, extracellularly released lactate dehydrogenase, Na-K-ATPase pump activity, and electron microscope studies. After 24 h of exposure, fluoride ion decreased cell number (-23%, P