PYREXAL AS FUNCTION TEST OF THE BONE MARROW IN FRACTIONATED AND SINGLE WHOLE-BODY IRRADIATION OF RATS

In rats irradiated with sublethal fractionated doses on the total-body bone marrow, tests were executed by means of Pyrexal. The substance was injected into the tail-vein. All additional measures as anesthesia, infusions, or antibiotics were omitted to avoid an effect on the bone marrow. It was found that with an increasing radiation dose, in addition to continuous decreass in white cells, the degree of increase of the number of granulocytes after Pyrexal injection is reduced. The curve is in correspondence with the expectations on the effect of total bcdy irradiation on the bone marrow. However, with respect to the applied total dose of 700 to 1400 r the resulting functional weakness of the bone marrow is small. This is similar for one-time irradiation. Apparently a breakdown of the regulation of leukocytes occurs only when the bone marrow is mostly destroyed 36 to 60 hours after the irradiation. The effect of the irradiation on the response of the bone marrow to Pyrexal results from a curve depending on dose and time. This allows conclusions on the applied radiation dose. (auth)