X-Irradiation and Bone Marrow

At 24 hours after a 600 r whole-body irradiation, the concentration of Fe/sup 59/, intracardially injected immediately after the irradiation appears to be significantly increased in the bone marrow of the rat. At the same time, the radioactivity in the peripheral blood cells is depressed to 2/3 of the activity found in the control animals. From these observations and from the study of the plasma clearance of Fe/sup 59/, it is concluded that this increased radioactivity of the hone marrow 24 hours after irradiation the Fe/sup 59/ having been injected immedately after the irradiation, is caused by the decreased output of Fe/sup 59/ tagged cells into the circulation. At 48 and 72 hours after irradiation, the uptake of Fe/sup 59/ in the bone marrow and in the blood is equally strongly depressed. (auth)