Separation of erythropoietin responsive cells in fetal mouse liver

Prostaglandins and erythropoiesis: structure/action relationships and identification of the prostaglandin responsive cells

Ten prostaglandin derivatives have been investigated for their ability to stimulate heme synthesis in serum-free cultures of fetal mouse liver cells in an attempt to define the structural requirements of the prostaglandin molecule necessary for erythrostimulation. In descending order of potency, only PGE2, PGF2 alpha and PGB1 produced at least 50% stimulation of endogenous heme synthesis. Seven of the ten prostaglandin derivatives tested were inhibitory at high concentrations. The PGE2 effect was pharmacologically distinct from that of Ep and could be antagonized by 15 epi PGF2 alpha. Unit gravity cell sedimentation studies demonstrated that PGE2 stimulated only the larger cells within the erythropoietin responsive cell population.

Investigations into the in vitro sensitivity to erythropoietin of haematopoietic tissue from ex-hypoxic, erythrocytotic mice

If 'sensitivity' is defined as the ratio of haem synthesis in erythropoietin (Ep)-stimulated cultures to that in cultures without added Ep, then haematopoietic tissue of ex-hypoxic mice is less sensitive to Ep in vitro than similar tissue from normal donors. This appears to be due primarily to the loss of erythropoietin responsive cells from the marrow and spleen. In addition, saline extracts of mature erythrocytes inhibited erythropoiesis in normal bone marrow cultures in a manner directly related to the 'haematocrits' used during their preparation. These data support recent suggestions that the preference of erythrocytotic mice over normal animals for Ep assay probably can be attributed to their low baseline level of erythropoiesis rather than an increased sensitivity to Ep.