Studies on Erythropoiesis IX. Mechanism of Decreased Erythropoiesis In Experimental Polycythemia

Abstract

Male albino rats were made polycythemic by blood transfusions. The rate of erythropoiesis was measured by the retlculocyte count and the incorporation of Fe59 into the red cells, and a depression was obtained in the polycythemic rats. This depression was reversed by subcutaneous injections of anemic rat plasma or the heat-denatured extract of anemic human plasma, both known to contain high titers of erythropoietin. Cobaltous chloride, which stimulates production of a high titer of erythropoietin, also reversed this depression. It was possible to suppress erythropoiesis completely, as measured by the reticulocyte count, in hypophysectomized hyper-tranfused rats. These experiments suggest the decreased erythropoiesis in rats with transfusion-induced polycythemia is the immediate consequence of a decreased titer of erythropoietin in these animals, and constitute further support for the theory of the humoral regulation of erythropoiesis.