EFFECTS OF COLONY-STIMULATING FACTORS ON VOLTAGE-GATED K-MARROW-DERIVED MACROPHAGES( CURRENTS OF BONE)

Murine bone marrow macrophages had been grown using either macrophage colony-stimulating factor (M-CSF) or granulocyte/macrophage colony-sti mulating factor (GM-CSF). The influence of these cytokines on appearan ce and properties of voltage-gated potassium currents was studied in t he macrophages derived from both cultures. Potassium currents were rec orded using the patch clamp technique in the whole cell configuration. Two different types of currents were investigated - inward rectifying (I-Ki) and outward K+ currents (I-Ko). Macrophages isolated from M-CS F or GM-CSF-supplemented culture exhibited either one of them or both currents simultaneously, However, a distinct distribution of these cur rents was observed: Whereas in the majority of M-CSF-cultured macropha ges I-Ki were detected (94%; n = 63), development of macrophages with GM-CSF resulted in the expression of I-Ko in a large number of cells ( 97%; n = 69). When both currents were expressed together in M-CSF-trea ted macrophages the amplitudes of most I-Ki were larger than those of I-Ko Opposite data were measured in the majority of GM-CSF-cultured ma crophages.