Differential effects of hyperoxia and hydrogen peroxide on thymidine kinase and adenosine kinase activities of cultured endothelial cells.
To compare the respective sensitivity of two nucleoside kinases, adenosine kinase and thymidine kinase, to oxidative stress, we measured these enzyme activities in cultured aortic endothelial cells exposed for 48 h to various O2 concentrations, and in cell extracts treated with H2O2 or the enzyme system hypoxanthine-xanthine oxidase. Adenosine kinase activity was not significantly influenced by the exposure to hyperoxia, nor by treatment with the enzyme system hypoxanthine-xanthine oxidase or with H2O2. On the other hand, there was a dose-dependent inhibitory effect on thymidine kinase activity resulting from exposure to various O2 concentrations or from treatment with various amounts of xanthine oxidase. Incubation of cell extracts in the presence of H2O2 also resulted in a significant reduction of thymidine kinase activity. These results indicate that thymidine kinase exhibits a selective sensitivity to the toxic effect of O2 concentrations and of O2 intermediates such as H2O2.
D000248:Adenosine Kinase / Q000037:antagonists & inhibitors*; D000818:Animals; D001011:Aorta; D002374:Catalase / Q000494:pharmacology; D002478:Cells, Cultured; D004727:Endothelium / Q000201:enzymology*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007700:Kinetics; D010100:Oxygen / Q000494:pharmacology*; D010770:Phosphotransferases / Q000037:antagonists & inhibitors*; D013482:Superoxide Dismutase / Q000494:pharmacology; D013552:Swine; D013937:Thymidine Kinase / Q000037:antagonists & inhibitors*; D014969:Xanthine Oxidase / Q000494:pharmacology
D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D010770:Phosphotransferases; D000248:Adenosine Kinase; D013937:Thymidine Kinase; D010100:Oxygen