Effects of colony-stimulating factors on voltage-gated K+ currents of bone marrow-derived macrophages

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