Effects of Folic Acid on the Anemia Induced by X Irradiation

Abstract

Previous work in this laboratory has shown that the anemia which followed radiations from internal and external sources was frequently macrocytic. 1 , 2 The macrocytosis may have been the result of damage directly to the bone marrow or indirectly through damage to the viscera, resulting in failure to form an anti-anemia factor. Folic acid, classified as a vitamin of the B complex, is reported to be similar in its action to liver extract. It has been shown to be effective therapeutically in certain of the macrocytic anemias in man. 3 , 4 It was without effect, however, upon the macrocytic anemia that resulted from administration of Sr⁸⁹. 5 , 6 Total-body X irradiation, unlike radioactive strontium, causes damage to the viscera as well as bone marrow. It is of interest, therefore, to determine the possible therapeutic effect of folic acid on the macrocytic anemia resulting from total-body X irradiation.

Male white rats were irradiated with 675 r (the approximate median lethal dose). Conditions of irradiation were: 200 Kv, 15 ma, 0.5 mm Cu and 1.0 mm Al filters, target field distance 72.5 cm, and exposure rate about 16 r per minute. One half of the irradiated animals were given intraperitoneal injections of folic acid daily, 5 days per week. The animals were divided into 3 groups and, treated as follows:

About 2 weeks after exposure the mean hemoglobin and erythrocyte values in the peripheral blood fell to about 70% of that of the control (Fig. 1). At most sampling intervals the irradiated group that received folic acid showed slightly higher values than the untreated irradiated group. The mean erythrocyte diameter was increased in the irradiated groups at 3 weeks after exposure and persisted for the duration of the observation.