Modulation of murine in vitro erythroid and granulopoietic colony formation by ouabain, digoxin and theophylline.
Ouabain has been shown to increase the number of clonally derived erythroid stem cells, CFUE and BFUE, from normal murine bone marrow. We report here that digoxin and theophylline also enhance erythroid stem cell colony formation, in the presence of suboptimal concentrations of erythropoietin (Ep) (0.01 IU/ml) in methylcellulose culture. Both digoxin and theophylline increased CFUE colony formation optimally at 10(-8) M (29-81% respectively). The increase in BFUE colony formation occurred at 10(-10) M (35-76% respectively), suggesting that BFUE are more sensitive to the enhancing properties of these compounds. In addition, digoxin theophylline and ouabain were effective inhibitors of clonally derived granulocyte-macrophage progenitor cells, CFUC, from normal murine marrow plated in double layer agar in the presence of 10% L-cell conditioned medium (LCM). The degree of reduction in colony formation by CFUC ranged from 11% to 100%. Digoxin and theophylline were inhibitory for CFUC in the range of 10(-2) to 10(-12) M; however, ouabain was inhibitory over a broader concentration range of 10(-4) to 10(-18) M, suggesting that ouabain has a greater influence on committed hematopoietic progenitor cell colony formation. Both ouabain and digoxin have the property of binding to Na+/K+ATPase. This may mediate the alteration of hematopoietic differentiation. Theophylline, an adenyl cyclase inhibitor, may act through alterations in cyclic nucleotide levels. These studies further indicate that digoxin, theophylline and ouabain may serve as useful tools in elucidating the underlying mechanisms of how specific growth factors influence hematopoietic growth and differentiation.
D000818:Animals; D000242:Cyclic AMP / Q000096:biosynthesis; D004077:Digoxin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004920:Erythropoiesis / Q000187:drug effects; D006098:Granulocytes / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000187:drug effects*; D066298:In Vitro Techniques; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D010042:Ouabain / Q000494:pharmacology*; D013806:Theophylline / Q000494:pharmacology*
D010042:Ouabain; D004077:Digoxin; D013806:Theophylline; D000242:Cyclic AMP