Radioprotective Effects of Dimethyl Sulfoxide in Golden Hamster Embryo Cells Exposed to γ Rays at 77 K: II. Protection from Lethal, Chromosomal, and DNA Damage

Golden hamster embryo cells were exposed to 137Cs gamma rays in the presence or absence of dimethyl sulfoxide at both 310 and 77 K. Dimethyl sulfoxide gave significant protection against cell killing at both 310 and 77 K. The extent of radioprotection with 1.28 M dimethyl sulfoxide at 77 K was 85-89% of the lethal effects observed in the absence of dimethyl sulfoxide at 310 K; the dose-modifying factor was 5.7. Dimethyl sulfoxide also exerted protected against gamma-ray-induced DNA single-strand breaks and chromosomal aberrations with a maximum protection of 80-100% at a dimethyl sulfoxide concentration of 1.28 M at 77 K. At 77 K, H atoms, ion holes, and electrons can migrate through frozen cells but OH radicals cannot diffuse. Thus the protective effects of dimethyl sulfoxide against cell killing, chromosomal aberrations, and DNA single-strand breaks at 77 K may be due to the scavenging of H atoms or other ions, rather than OH radicals.