Action of misonidazole on L5178Y-R and L5178Y-S cells. II. Cytotoxicity and radiosensitization under hypoxic conditions.

Misonizadole exerts an equal cytotoxic effect on L5178Y-R and L5178Y-S cells; 5 mM misonidazole sensitizes cells of both strains to a similar extent under hypoxic conditions: the effect of drug in 59% of the oxygen effect in L5178Y-R cells and 52% in L5178Y-S cells. It was previously reported that the amount of initial DNA damage determined by the alkaline unwinding technique is 1.3 times lower in irradiated hypoxic L5178Y-R cells than in L5178Y-S cells. Hence it seems that the drug ability to sensitize these cell strains does not depend on amount of initial DNA damage available for interaction. Although the examined L5178Y strains differ in radiosensitivity, their ability to repair oxygen and misonidazole-dependent cellular damage is similar.