[Effects of hyperoxic exposure on hemopoiesis]

Effects of oxygen inhalation on hemopoiesis were investigated in mice and following results were obtained. 1) The numbers of pluripotent hemopoietic stem cells (CFU-S) and granulocyte-macrophage progenitor cells (GM-CFC) in murine bone marrow and spleen decreased significantly from day 1 of exposure to 70% and 100% oxygen. 2) The numbers of CFU-S and GM-CFC did not recover in mice that were exposed to 100% oxygen for 1 and 2 days followed by air exposure for 7 days. These results suggest that inhalation of more than 70% oxygen for 1 day induces inhibitory effects of the hemopoietic stem cells, and 100% oxygen exposure over 1 day can cause irreversible damage to the hemopoiesis.