The effects of combined administration of two drugs elevating extracellular adenosine, namely dipyridamole (DP) and adenosine monophosphate (AMP), and granulocyte colony-stimulating factor (G-CSF) on hemopoietic stem cells in vivo were investigated. The experiments were performed on mice using the endogenous spleen colony formation in gamma-irradiated animals as an endpoint. The results have shown that DP and AMP act additively with G-CSF to enhance spleen colony formation and thus the erythroid repopulation of the spleen. These findings indicate that the signaling pathways of G-CSF and drugs elevating extracellular adenosine can interact at the level of primitive hemopoietic stem cells. The enhancement of hemopoiesis-stimulating effects of G-CSF by DP and AMP, which are low-priced and clinically available drugs, could improve the cost-effectiveness of the therapy with G-CSF., M. Hofer, M. Pospíšil, J. Netíková, V. Znojil, J. Vácha., and Obsahuje bibliografii