title: Enhancement of radiation sensitivity by postirradiation hypoxia: time course and oxygen concentration dependency.
abstract: We have recently demonstrated that postirradiation hypoxia during colony formation in vitro enhanced the radiation sensitivity of murine tumor cells irradiated and maintained at 0.1% O2. The effect of postirradiation hypoxia was expressed by a significant reduction in the oxygen enhancement ratio. We now demonstrate that this enhancement of radiation sensitivity by postirradiation hypoxia is also observed in a human tumor cell line. The effect was observed at [O2] less than or equal to 0.1%, but was not present at [O2] greater than or equal to 0.5%. Time-course experiments suggested that this enhancement of cell killing by X rays required prolonged exposure to hypoxic conditions.
authors.affiliation: Department of Internal Medicine, University of Texas Medical Branch, Galveston 77550.
authors.forename: V
authors.initials: V
authors.lastname: Gupta
authors.forename: J A
authors.initials: JA
authors.lastname: Belli
mesh_terms: D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D006224:Cricetinae; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D010100:Oxygen / Q000502:physiology*; D011836:Radiation Tolerance; D013997:Time Factors
chemical_list: D010100:Oxygen