Enhanced erythropoiesis induced by hypoxia in hypertransfused, post-hypoxic mice

The erythropoietic response, measured as RBC-59Fe uptake after 24 h-exposure to hypoxia, were determined in posthypoxic, "acute" and "chronic" hypertransfused, and posthypoxic-hypertransfused mice. Radioiron uptake by erythrocytes was about 25 times greater in post-hypoxic than in both types of hypertransfused mice. Posthypoxic-hypertransfused mice showed an erythropoietic response to hypoxia which was not significantly different from that of posthypoxic mice and about 20 times greater than those of "acute" and "chronic" hypertransfused mice. When hypertransfused mice were exposed to hypoxia before transfusions, a linear increase in 59Fe uptake values in response to hypoxia was observed with exposures between 6 and 30 h. No further increase was observed for exposures of 46 to 216 h. These results suggest a sensitization of the erythropoietin-producing organ(s) by hypoxia.