| Abstract: | The toxicity of misonidazole (MISO) to hypoxic Chinese hamster ovary (CHO) cells in serum-free medium is enhanced by Fe(III)-EDTA. Enhancement of MISO cytotoxicity by a factor of 1.6 was seen with 2 microM Fe(III)-EDTA, while 200 microM Fe(III)-EDTA results in sensitization by a factor of 2.0. Treatment of CHO cells with the iron chelator desferal resulted in protection against the hypoxic cytotoxicity in MISO (approximate protection factor of 2.5 with 100 microM desferal). Similar results were obtained with Chinese hamster V79 cells. Fe(III)-EDTA also enhanced binding of 2-14C] MISO to cellular macromolecules while desferal decreased binding of MISO to cellular macromolecules. These results suggest that iron plays an important role in the reductive metabolism of MISO and that modification of the intracellular metal ion status may be a useful approach to modulating the biological effect of nitro compounds. |
