[Combined effects of prolonged hypokinesia and ionizing radiation on the hematopoietic system and lymphatic organs of rats].

During interplanetary missions ionizing radiations blended with other debilitating non-radiation environmental agents which can modify the radiobiological effect make up a risk factor. Still, the experimental data about the direction of the modifying action are conflicting and diverge from an increase to a depression of radioresistance. In this work we investigated the influence of prolonged hypokinesia on early radiobiological effects. The experiment was conducted with Wistar rats exposed to acute gamma-radiation at a dose of 7.5 Gy after 25 days of head-down immobilization. In the period of one month since exposure the morphological properties of peripheral blood and bone marrow, cell composition and mass of thymus, spleen and adrenal masses have been investigated. A significant, 1.5-2-fold, inhibition of recovery rate was displayed by each sprout of the blood-forming and especially thymolymphatic systems (2.5-3 folds) resulting from combined stress, whereas the depth of radiation damage in terms of maximum degree of the bone marrow tissue depopulation, cytopenia of peripheral blood and mass losses of lymphoid organs was of little difference in the two groups.