TEMPERATURE-DEPENDENT INFLUENCE OF THIOLS UPON GLUTATHIONE LEVELS IN CHINESE-HAMSTER OVARY CELLS AT CYTO-TOXIC CONCENTRATIONS

  • 1 January 1985
    • journal article
    • research article
    • Vol. 45  (12) , 6219-6224
Abstract
Chinese hamster ovary cells were exposed to the sulfhydryl compound cysteamine at different temperatures (5.degree. C, 37.degree. C, 44.degree. C) at concentrations known to generate activated oxygen species. At 37.degree. C, the cellular glutathione (GSH) content increased linearly over the time of drug exposure(2 h) as compared to untreated cells or to cells kept at 5.degree. C during drug treatment. The 2-4 fold increase in GSH induced by cysteamine was more rapid at 44.degree. C than at 37.degree. C and showed a saturation effect at the higher temperature. The elevation of GSH could be completely blocked by DL-buthionine-S,R-sulfoximine, an inhbitor of .gamma.-glutamylcysteine synthetase, or by incubation in a cystine-free medium during the period of drug treatment. The increased cellular GSH content induced by cysteamine alone at 37.degree. C or combined with heat at 44.degree. C decreased to the range of control values within 22 h after either treatment. Other thiols like cysteamine, namely cysteine, N-acetylcysteine, and dithiotheitol, werd found to be similar in their potential to induce GSH elevation in Chinese hamster ovary cells. Cytotoxic effects of these sulfhydryl compounds were observed in the same concentration range as that for cysteamine(0-2 mM), but only if cells were plated at low densities (102-104 cells/flask), and were completely blocked by the addition of catalase (50 .mu.g/ml). In contrast, the elevation of GSH after thiol treatment (0.8 mM) was not modified by catalase. The data suggest that thiol treatment combined with hyperthermia leads to a rapid increase of GSH biosynthesis in Chinese hamster ovary cells which seems to be independent of the simultaneous generation of activated oxygen species by thiol autoxidation.