Effect of Intermittent Hypoxia on Regeneration of Haemopoiesis in Rats Treated with Cyclophosphamide or Total Body Irradiation

Abstract

Effects of intermittent hypoxia on regeneration of haemopoiesis in rats treated with cyclophosphamide or total body irradiation are described. The rats were exposed to a gas mixture consisting of 10 per cent oxygen and 90 per cent nitrogen within half‐an‐hour after treatment. The exposure to hypoxia lasted for SV2 hours daily. The irradiated and cyclophosphamide treated animals differed markedly in their response to hypoxia. Thus, in the cyclophosphamide treated animals hypoxia induced a steady increase in red cell production following the initial stop in erythropoiesis caused by the treatment. In contrast, in the irradiated rats recovery was more slow and furthermore, a second failure of erythropoiesis occurred during recovery. This second failure of red cell production coincided with the second failure of the myelopoiesis in the same animals. Although total body irradiation and cyclophosphamide treatment caused initially about the same extent of marrow hypoplasia, the present results indicate that irradiation caused more damage to the stem cells than did cyclophosphamide.