Radiosensitivity of animals exposed to ionizing radiation in gaseous medium

Inhalation of pure oxygen by (CBAxC57B1) and C57B1 female mice aggravates radiation damage to the intestine which is manifested by the increased radiation inhibition of mitotic activity in epithelial cells of duodenum and by marked hypoplasia of its mucosa. The oxygen effect on radiosensitivity of hemopoietic tissues is function of radiation dose. The unfavourable effect of oxygen on the hemopoietic system was only observed at fatal radiation doses; it was manifested by increased hypoplasia of bone marrow, spleen and thymus. At sublethal doses of γ-quanta, no unfavourable action of oxygen on the course of bone-marrow syndrome of radiation sickness was revealed. Under these conditions, a higher proliferative activity of bone marrow was registered at early postradiation periods. Inhalation of pure oxygen by intact animals elicits inhibition of mitotic activity in bone marrow and does not affect the rate of cell fision in crypts of small intestine mucosa