Protection against radiation induced chromosome injury by sulfhydryl compounds.

The radiation induced changes in a critically radiation-sensitive tissue, bone marrow of Swiss albino mice and its modification by two sulfhydryl compounds, MPG and WR-2721, were studied cytogenetically after whole body exposure to 0.5, 1.5, 3.0, 4.5 and 6.0 Gy of 60Co gamma radiation. The changes in the structural arrangements of chromosomes in the bone marrow were studied at various post-irradiation times from 1 to 28 days. Both the control (irradiated) and experimental (drug + irradiation) animals showed qualitatively similar types of aberrations; the severity of lesions increased with the radiation dose. The maximum damage in all the groups was seen on day 1, post-irradiation. Both the drugs afforded better protection at lower doses of exposure, their effectiveness decreasing with an increasing radiation dose. Of the two drugs, WR-2721 was more effective than MPG against initial aberration yield but the former, at the present drug dose, showed some toxic effect at the later post-irradiation intervals (2 weeks onward) as manifested by an increase in the chromatid breaks and polyploidy.