Comparison of the effects of crude and purified erythropoietin on the synthesis of hemoglobin in rat bone marrow cell cultures.
The stimulatory effects of crude (148 U/mg protein) and purified (15,920 U/mg protein) human urinary erythropoietin (Ep) on heme and globin synthesis of rat bone marrow cells in short term (2-3 day) suspension culture were compared. Freshly isolated, unfractionated marrow cells responded equally well to both Ep preparations. Velocity sedimentation at unit gravity was used to separate the marrow cells into a fast-moving (population I) and a slow-moving (population II) fraction. Of the 2 preparations tested, only crude Ep was found to stimulate heme and globin synthesis of population I cells. Population II cells were unresponsive to both Ep preparations. Preincubation of the rat marrow cells in the absence of Ep for 48 h resulted in the disappearance of most of population II, the remaining cells only responded to the crude Ep preparation. Direct remixing experiments involving various proportions of population I and II cells also showed that addition of the purified Ep preparation could only bring about an increase in hemoglobin synthesis in those cultures which contained a sufficient number of population II cells. Cultures deficient in population II cells to which the crude Ep preparation was added did not show this requirement, suggesting that this preparation contained a component which could substitute for the presence of population II cells. This demonstrates that the action of Ep and of a second factor (or of a cell to cell signal) is required to increase hemoglobin synthesis in short term rat marrow cell cultures.
D000818:Animals; D001853:Bone Marrow / Q000378:metabolism*; D002469:Cell Separation; D002478:Cells, Cultured; D004921:Erythropoietin / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000187:drug effects; D006454:Hemoglobins / Q000096:biosynthesis*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D006454:Hemoglobins; D004921:Erythropoietin