The effects of hemorrhage, hypoxia, and a preparation of erythropoietin on thrombopoiesis.

Abstract

The effects of hemorrhage, hypoxia, or a preparation of erythropoietin on platelet production were investigated by measuring incorporation of selenomethionine-75Se (75SeM) into the platelets of rabbits or mice. Rabbits that were bled daily for 5 days had a significant increase in the platelet count, 48 hours after cessation of hemmorrhage, that coincided with a threefold increase in isotope incorporation into platelets. Mice that were bled daily for 3 days also had significantly higher platelet counts and a 38 per cent increase in incorporation of isotope into platelets, 3 days after the last hemorrhage. Normal rabbits, injected with plasma from repeatedly bled, anemic, and moderately thrombocytopenic rabbits, had a 58 per cent greater maximum incorporation of 75SeM than did control animals. Mice exposed to hypoxia for 6 days had a mean platelet count 23 per cent lower than normal controls, but no change in incorporation of 75SeM into platelets. Plasma from hypoxic mice did not stimulate platelet production when injected into normal mice. A preparation of human urinary erythropoietin (15 to 30 U. per mouse or 30 to 120 U. per rabbit) significantly increased incorporation of isotope into the platelets of normal mice and rabbits. The results demonstrated that hemorrhage, but not hypoxia, is associated with increased thrombopoietic activity in plasma. However, large doses of preparations of human erythropoietin contained detectable thrombopoietic activity.