Stimulation of Erythropoiesis in Irradiated Dogs and Rats

Abstract

[long dashh]The usual suppression of erythropoiesis in dogs following exposure to a sublethal dose of whole body irradiation (150 r Co60 source) was modified by the removal of 30% of the blood volume immediately before or after irradiation. During the first 20 post-irradiation days, control irradiated dogs had a progressive decline in hematocrit, accompanied by a decrease in reticulocytes and the rate of Fe59 incorporation. In the bled and irradiated dogs, there was a return of the hematocrit toward normal during this period, along with reticulocytosis and normal or increased Fe59 incorporation. In rats, post-irradiation administration of para-aminopropriophenone as well as bleeding immediately before or after whole body irradiation (200 r), produced a significant increase in the Fe59 incorporation and reticulocyte values over those of control irradiated rats. Bleeding 24 hours after irradiation had no apparent effect. The data indicate the reversibility or modification of radiation injury to erythropoiesis. The possibility is suggested that this effect is produced by the release of a humoral factor in response to hypoxia.