Effect of Repeated Roentgen or Neutron Irradiation on the Hematopoietic System

Groups of six mongrel dogs were subjected repeatedly to either 150 rads of x rays or 150 reads of neutrons at 3-month intervals. A third group of six nonirradiated dogs was the control for any possible age or seasonal effects. After each of the four irradiation exposures, various hematological parameters were studied. It was observed that, while the dog normally incorporates nearly all the injected Fe/sup 59/, a 150-rad dose of either x rays or neutrons reduces iron uptake to 70 % of the injected dose. Similarly to what was previously reported for the rat, with each repeated irradiation a reduction below the iron incorporation value obtained in the previous exposure may be observed. The data may again best be described with a simple exponential equation. Although hematocrit values did not change until after the third irradiation, the erythrocyte volume decreased continuously, which further implicates residual radiation effects to the erythropoietic system. The employed radiation dose caused the characteristic decrease in peripheral leukocyte and platelet values, and complete recovery was not observed with repeated exposures. In general, the effects of x irradiation on leukocyte and platelet counts appeared to be greater than those of neutron irradiation. Finally, whereas four outmore » of six x-irradiated dogs died after four replicated exposures, only one neutron-exposed dog did not survive. (auth)« less