Interaction of nitroimidazole sensitizers and oxygen in the radiosensitization of mammalian cells at ultrahigh dose rates
When CHO cells, equilibrated with 0.44% oxygen, are irradiated with single 3-nsec pulses of electrons from a 600-kV-field emission source, a breaking survival curve is observed. The breaking behavior, believed to be the result of radiolytic oxygen depletion, can be prevented by the presence of a relatively low concentration of the hypoxic cell sensitizer misonidazole; similar results are obtained with metronidazole and Ro-05-9963. The resulting survival curves exhibit a sensitized response similar to that obtained with conventional dose rate radiation for CHO cells under this oxygen concentration. This degree of sensitization is greater than that observed for CHO cells irradiated at ultrahigh dose rates under the same concentration of sensitizer in nitrogen. The data suggest that the nitroimidazole compounds interfere with the radiation chemical oxygen depletion process and that the radiosensitization observed in the nonbreaking survival curve is the consequence of sensitization by both the nitroimidazole and, primarily, the oxygen rather than a direct subsitution for oxygen by the sensitizer. This conclusion is also supported by data obtained in double-pulse experiments. The results are discussed with regard to the mechanisms of the oxygen depletion process and radiosensitization.
- Research Organization:
- Massachusetts General Hospital, Boston
- OSTI ID:
- 6538310
- Journal Information:
- Radiat. Res.; (United States), Vol. 85:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CELL CULTURES
BIOLOGICAL RADIATION EFFECTS
IMIDAZOLES
RADIOSENSITIVITY EFFECTS
OXYGEN
DOSE-RESPONSE RELATIONSHIPS
EXTERNAL IRRADIATION
HAMSTERS
RADIATION DOSES
RADIOSENSITIVITY
SURVIVAL CURVES
ANIMALS
AZOLES
BIOLOGICAL EFFECTS
DOSES
ELEMENTS
HETEROCYCLIC COMPOUNDS
IRRADIATION
MAMMALS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RADIATION EFFECTS
RODENTS
VERTEBRATES
560121* - Radiation Effects on Cells- External Source- (-1987)