title: Radiobiologic response of CHO-KI cells treated with vitamin A.
abstract: Treatment of CHO-KI cells with vitamin A altered their response to subsequent gamma irradiation. In general longterm preincubation with low doses of the vitamin caused a relative increase in the number of cells surviving a given radiation dose. The effect resulted in an increase in the D0 of the survival curve. Long or short term exposure to high concentrations of the vitamin caused a decrease in the number of surviving cells leading to a decrease in the extrapolation number of the survival curve. Recovery of cells from radiation damage, assessed using the split dose technique, was also impaired by vitamin A pretreatment. A mechanism involving repair of potentially lethal damage may explain the protective effect of vitamin A since this was highly dependent on the cell density of cultures at the time of irradiation. However, in view of the data showing that the vitamin A concentrations necessary to alter the radiation survival curve shoulder caused a significant release of sialic acid into the medium, a mechanism involving membrane stability may account for both the reduction in repair/recovery capacity of the treated cells and the radioprotective effect.
mesh_terms: D000818:Animals; D002455:Cell Division; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects*; D003037:Cobalt Radioisotopes; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D010053:Ovary; D013997:Time Factors; D014801:Vitamin A / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D003037:Cobalt Radioisotopes; D014801:Vitamin A