Erythropoietin formation in rats with experimental hypersplenism.

Splenomegaly accompanied by anaemia, increased reticulocyte and decreased thrombocyte counts, was induced in Wistar rats by a long-term intraperitoneal administration of methylcellulose. Compared to controls, hypersplenic rats showed significantly enhanced utilization of 59-Fe by red cells and increased titre of erythropoietin. After the exposure of rats to hypoxic hypoxia corresponding to an altitude of 7,000 m for 6 h, no difference in the erythropoietin titre was found in either group. The results suggest that experimental hypersplenism alone does not affect the production of erythropoietin and does not stimulate the formation of an inhibitor of erythropoietin or erythropoiesis. The increased titre of erythropoietin and enhanced utilization of radioiron by red cells in rats with hypersplenism were found to be due to haemolytic anaemia leading to the stimulation of erythropoiesis.