Fluoride ion toxicity in rabbit kidney thick ascending limb cells.
OBJECTIVE
Some halogenated agents, especially methoxyflurane, because of a higher level of fluoride production, induce a renal concentrating defect that could be related to an ascending limb impairment. We investigated the mechanisms of fluoride toxicity on an immortalized cell line.


METHODS
Cells were cultured for 2, 6 or 24 h in the presence of fluoride. Toxicity evaluation was based on: cell numbers, protein content, leucine-incorporation, lactate dehydrogenase (LDH) and N-acetyl-beta-glucosaminidase (NAG) releases, Na-K-ATPase and Na-K-2Cl activities, electron microscope studies. Infrared analysis and fluoride microdetermination allowed crystal components.


RESULTS
At 5 mmol after 24 h, fluoride decreased cell numbers (-14%, *P < 0.05), protein content (-16%*), leucine incorporation (-54%*), Na-K-2Cl activity (-84%*), increased LDH (+145%*) and NAG release (+190%*). Na-K-ATPase was more sensitive and impaired from 1 mmol for 24h and after 2 h at 5 mmol. Crystal formation in mitochondria occurred after 6 h at 5 mmol. Infra-red analysis and fluoride microdetermination established that crystals contained sodium, phosphate and fluoride.


CONCLUSIONS
The results suggest that the Na-K-ATPase pump is a major target for fluoride toxicity in Henle's loop.
Cittanova
M L
ML
Département d'Anesthésie-Réanimation, Hĵpital Pitié-Salpêtrière, Paris, France. marie-laure.cittanova@psl.ap-hop-paris.fr
Estepa
L
L
Bourbouze
R
R
Blanc
O
O
Verpont
M C
MC
Wahbe
E
E
Coriat
P
P
Daudon
M
M
Ronco
P M
PM
D000118:Acetylglucosaminidase / Q000187:drug effects; D018685:Anesthetics, Inhalation / Q000494:pharmacology / Q000633:toxicity*; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005459:Fluorides / Q000494:pharmacology / Q000633:toxicity*; D008138:Loop of Henle / Q000166:cytology / Q000000981:diagnostic imaging / Q000187:drug effects*; D008854:Microscopy, Electron; D011817:Rabbits; D028021:Sodium-Potassium-Chloride Symporters / Q000187:drug effects*; D014463:Ultrasonography
D018685:Anesthetics, Inhalation; D028021:Sodium-Potassium-Chloride Symporters; D000118:Acetylglucosaminidase; D005459:Fluorides