Cytotoxicity of misonidazole and DNA damage in hypoxic mammalian cells

The loss of colony-forming ability and the yield of DNA single strand breaks were studied following exposure of various mammalian cell types to misonidazole. A correlation was observed between cell inactivation and DNA damage. If, after exposure, the cells were washed free of the drug and then incubated at 37 degree C in growth medium, it was observed that surviving cells repaired their DNA to the point that sedimentation profiles were identical to those of unexposed cells. In nonsurviving cells, however, the DNA was found to be further degraded with post-exposure incubation.