Evidence of Circulatory Failure in the Early Radiation Response of the Chicken

¹ From the Division of Biological and Medical Research, Argonne National Laboratory, Lemont, Illinois

The early radiation syndrome in the chicken is distinct from that associated with death several days after exposure. In both young chicks and adult roosters, the mode of early death is characterized by a progressive circulatory collapse. To obtain more precise estimates of the circulatory changes in the initial postirradiation period, we have measured total peripheral blood volume and the blood volume of several visceral organs and of skeletal muscle. Determinations were made on control and x-irradiated chicks and adult roosters. In chicks the postirradiation decrease in actively circulating blood volume ranged from 30 to 60%. Previous studies of hemorrhagic hypotension in chicks have shown that loss of one-third of the circulating blood volume was sufficient to produce irreversible shock and renal failure. Roosters, however, can compensate for much greater loss in blood volume. Loss by hemorrhage of more than 60–70% of the normal circulating volume is frequently required to produce irreversible shock. In x-irradiated roosters, values obtained from the peripheral blood indicated no decrease in volume of circulating red cells and a 30% decrease in plasma volume. The distribution of erythrocytes and plasma, however, was significantly altered. The decrease in circulating blood volume was most marked in liver, spleen and kidneys and was probably sufficient to cause a significant decrease in function.