EFFECT OF RECOMBINANT-HUMAN-ERYTHROPOIETIN ON BLOOD RHEOLOGY OF RAT

Recombinant human erythropoietin (rhEPO; 180 or 1800 IU per kg) was daily administered to 6 weeks old rats for 1 to 2 weeks. [1] The increase of blood viscosity in rhEPO-administered rats in a saturation manner entirely depends on the hematocrit (the plasma viscosity and the plasma protein composition were not altered by rhEPO-administration). [2] No change in red cell deformability was observed upon rhEPO administration. [3] The velocity of rouleaux formation in autologous plasma decreased in rhEPO-administered rats. [4] A considerable polycythemia with reticulocytosis was induced in dose- and duration-dependent manners but in a saturation manner: cell volume increased and intracellular hemoglobin concentration inversely decreased. The density distribution of red cells shifted towards low specific gravity and became heterogenous. [5] No drastic alterations in contents of 2,3-diphosphoglycerate and ATP were detected. In conclusion, the increase of blood viscosity upon daily administration of rhEPO was hematocrit-dependent, regardless of the appearance of red cells with large volume and low internal viscosity.