Effects of ouabain and valinomycin on in vitro erythroid colony formation (CFU-e and BFU-e)

Ouabain enhances the number of clonally derived erythroid stem cell colonies (CFU-e and BFU-e) from normal murine bone marrow. Ouabain is known to inhibit lymphocyte proliferation by blocking the Na+/K+ pump. To further explore these Na+/K+ ATPase-associated interrelationships, valinomycin, an inhibitor of Na+/K+ ATPase was employed. The addition of valinomycin (10(-11) to 10(-15) M) in the presence of ouabain and erythropoietin (Ep) did not alter the erythroid colony-forming stimulation which was characteristic of cultures in which only ouabain (10(-15) M) and Ep were added. Valinomycin did effectively block both CFU-e and BFU-e formation when it was added in the range of 10(-3) to 10(-9) M. The mechanism of this valinomycin-induced inhibition and ouabain stimulation is discussed.