Fatty acid cytotoxicity to bovine lens epithelial cells: investigations on cell viability, ecto-ATPase, Na(+), K(+)-ATPase and intracellular sodium concentrations.
Unsaturated non-esterified fatty acids have been shown to be cytotoxic in micromolar concentrations to bovine lens epithelial cells, in the following order: arachidonic acid > linoleic acid > oleic acid = linolenic acid. As unsaturated free fatty acids are known to be Na(+), K(+)-ATPase inhibitors, the aim of the study was to investigate whether or not the fatty acid cytotoxicity is correlated with effects on Na(+), K(+)-ATPase activity and function in bovine lens epithelial cells. Furthermore, we also examined the effects of linoleic acid on an ecto-ATPase activity which could be demonstrated on the outside of primarily cultured bovine lens epithelial cells. It has already been shown that 10 micro mol l(-1)linoleic acid was cytotoxic but did not impair the ecto-ATPase activity of intact cells nor the Na(+), K(+)-ATPase in enriched membrane fractions. Na(+), K(+)-ATPase activity was slightly activated with 10 micro mol l(-1)linoleic acid and inhibited by about 50% with 100 micro mol l(-1). Using the sodium-binding benzofuran isophthalate, measurements of intracellular sodium concentrations were carried out. In serum-starved bovine lens epithelial cells the basal [Na(+)](in)was clearly lower than 5 mmol l(-1). When the function of the Na(+), K(+)-ATPase was interrupted by omitting K(+)-ions from the medium, [Na(+)](in)increased at a rate of 0.318 mmol l(-1)min(-1). Linoleic acid intensified that increase strongly in a concentration dependent manner. However, in K(+)-containing medium the linoleic acid-induced increase of [Na(+)](in)was completely prevented. Therefore, the high linoleioc acid cytotoxicity cannot be mediated by linoleic acid effects on Na(+), K(+)-ATPase activity and function in bovine lens epithelial cells.
Nguyen
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Institut für Physiologische Chemie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany.
Glanz
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Glaesser
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D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D002417:Cattle; D002470:Cell Survival; D002478:Cells, Cultured; D003603:Cytotoxins / Q000502:physiology*; D004847:Epithelial Cells / Q000737:chemistry / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000502:physiology*; D007908:Lens, Crystalline / Q000166:cytology*; D012964:Sodium / Q000032:analysis; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis
D003603:Cytotoxins; D005230:Fatty Acids, Nonesterified; D012964:Sodium; D000251:Adenosine Triphosphatases; D000254:Sodium-Potassium-Exchanging ATPase