Proliferative and maturative behaviour patterns on murine bone marrow and spleen erythropoiesis along hypoxia

The present study was performed to determine quantitative and qualitative effects of hypoxia on murine erythron, CF1 mice were submitted to hypobaric hypoxia (HH) along 18 days. The proliferative response to recombinant human erythropoietin (rHuEPO: 0-250 mU/ml) was analyzed by DNA assays from bone marrow and spleen cells at different times. Bone marrow proliferative response showed a slight increment under stress but remained over control by the end of the experience. Splenic erythroid proliferative response was observed at a maximum rate on day 6 of HH (26 fold) and returned near to control values after day 10. The assessment of erythropoietic maturative pattern was performed by 59Fe uptake assays. Total nuclear cell counts increased in both tissues (1.5 times in marrow and 5 times in spleen) under hypoxia. In addition, percentages of different lineages (erythroid, myeloid and lymphoid) were scored. Total erythroid marrow cell counts increased in a narrowly degree and persisted above basal counts after day 18. Meanwhile, splenic red cells rose to 30 times over control on day 6 and failed sharphy near control values from day 12 of HH. Splenic red cells contribution was approximately 60 percent of total production between 6-8 days. By the end of the assay bone morrow took back erythroid command (90 percent). These findings indicate correlation between the time course as well as quantitative and qualitative parameters in the patterns of proliferation and maturation. Moreover, the erythron response to hypoxia, seemed to be related to microenvironmental regulations rather than to hormonal variances.

Comparative studies of erythroid growth factors

Se evaluó la aparición de factores séricos capaces de estimular la proliferación de progenitores eritroides mamíferos. Sueron anémicos y normales de ambos e jemplares, fraccionados por tratamiento alcohólico, se ensayaron por el método del ratón post-hipóxico, no detectándose incorporación de 59Fe. Al ser ensayados en cultivos semisólidos de médula ósea murina a diferentes tiempos de incubación (colonias CFU-E y BFU-E), el suero anémico aviario mostró alta actividad estimulatória, mientras que el suero anémico anfibio resultó incapaz de incrementar la proliferación eritroide. La muestra aviaria parcialmente purificada por tratamiento alcohólico fue cromatografiada en Sephadex G-150 revelando tres entidades moleculares respondables de la actividad biológica in vitro, con pesos moleculares aparentes de 29, 14 y 10 KD respectivamente. Los factores séricos aviarios estimulantes de la línea eritroide fueron sometidos a diversos tratamientos físico-químicos y luego se evaluó la conservación de su actividad biológica. Todos ellos resultaron termoestables, sensibles al tratamiento con neuraminideasa, mientras que el ditiotreitol provocó la pérdida de la actividad biológica de las proteínas de bajo peso molecular. Estos resultados sugieren, al menos bajo estas condiciones experimentales, la presencia de factores análogos estimulantes del crecimiento eritroideo entre amniotas homeotermos