Reactivation of Erythropoiesis by Cobalt after Radiation Injury

The ability of cobalt chloride to prevent the anemia following total body irradiation injury was tested. Laboratory albino rats were exposed to a single x-ray dose of 250 or 350 r. After the exposure, one-half of the rats were treated with daily subcutaneous injections of cobalt while the others were given saline injections at the same time. The first injection was administered 1 hour after the exposure and the daily dose consisted of 0.8 mg. of cobalt per Kg. of body weight. The treatment was continued over a period of 8 weeks. Hemoglobin and the erythrocyte count were measured once a week.

Rats exposed to 250 r and thereafter treated with cobalt showed reactivation of erythropoiesis after 1 to 2 weeks and the animals then rapidly developed polycythemia, in contrast to the similarly irradiated rats afterwards treated with saline, which after 8 weeks still had blood values below the original level. In rats irradiated with 350 r, the same phenomenon was seen, although the effect of cobalt became apparent slowly. The findings observed in the peripheral blood were confirmed by checking the bone marrow of rats given 350 r.

Besides the erythropoietic effect, toxic symptoms were observed. The toxicity and made of action of cobalt are discussed.