Feedback Regulation by Red Cell Mass of the Sensitivity of the Erythropoietin-producing Organ to Hypoxia

The effects of short intervals of anemic, hypoxic and CO hypoxia of various degrees on erythropoietin production have been compared in anemic, normal and polycythemic rats. The anemic and CO hypoxia were terminated by the exposure of rats to hyperbaric oxygen. The duration of hypoxic periods of different types of hypoxia ranged from 15 to 120 minutes. The decreased response of erythropoietin production to hypoxia was observed in rats having higher hematocrit. It is assumed that there is feedback inhibition, by the circulating red cell mass, of the sensitivity of the erythropoietin-producing organ to hypoxia.