Chromosome aberrations reduced in whole-body irradiated mice by pretreatment with cyanide.

Male mice exposed to single, whole-body 60Co irradiation, were injected intraperitoneally with a non-toxic dose of KCN, 2 min or 20 min prior to irradiation. Bone-marrow cells were examined for chromatid breaks and chromosome aberrations (CA) at different times post-irradiation. The 2 min but not the 20 min treated mice had a marked reduction in chromatid breaks and chromosome aberrations. A study was made of mice exposed to 3.0 Gy (1.8 Gy/min), treated with KCN 2 min prior to irradiation and examined 5 min to 30 d post-irradiation. After 5 min there were no significant changes in frequency of CA. Subsequently, the incidence of CA in the KCN-treated group was reduced compared to the irradiated controls. By the 30th day, however, CA frequencies had returned to control levels in all groups. No effect of KCN treatment was observed in the white or red blood cells. The cytogenetic results were posited to be a function of the relative inhibition and recovery times of cyanide affected cytochrome oxidase, DNA synthesis, and ATP.