Properties of voltage-gated currents of microglia developed using macrophage colony-stimulating factor |
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Authors: | Claudia Eder Hans -Georg Fischer Ulrich Hadding Uwe Heinemann |
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Affiliation: | (1) Institut für Neurophysiologie, Zentrum für Physiologie und Pathophysiologie, Universität zu Köln, Robert-Koch-Strasse 39, D-50931 Köln, Germany;(2) Institut für Medizinische Mikrobiologie und Virologie, Heinrich-Heine-Universität, Universitätsstrasse 1, D-40225 Düsseldorf, Germany;(3) Abt. Neurophysiologie, Institut für Physiologie der Charité, Humboldt Universität, Tucholsky Strasse 2, D-10117 Berlin, Germany |
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Abstract: | Microglia were isolated from a murine neonatal brain cell culture in which their development had been stimulated by supplementation with the macrophage/microglial growth factor macrophage colony-stimulating factor (M-CSF). Using the whole-cell configuration of the patch-clamp technique, voltage-gated membrane currents were recorded from these microglial cells. Hyperpolarization induced inward rectifying K+ currents, as described for microglia from untreated cultures. These currents activated negative to the K+ equilibrium potential and, with a strong hyperpolarization, displayed time-dependent inactivation. The inactivation was abolished when extracellular NaCl was replaced by N-methyl-d-glucamine (NMG), thereby indicating a partial block of this K+ conductance by Na+. Inward rectifying currents were also blocked by extracellularly applied Cs+ or Ba2+. They were slightly diminished following treatment with extracellular tetraethylammonium chloride (TEA) but were not affected by 4-aminopyridine (4-AP). Upon long lasting depolarizing voltage pulses to potentials positive to 0 mV, the cells exhibited a slowly activating H+ current which could be reduced by application of inorganic polyvalent cations (Ba2+, Cd2+, Co2+, La3+, Ni2+, Zn2+) as well as by 4-AP or TEA. Based on their kinetics and pharmacological characteristics, both currents detected on M-CSF-grown microglia are suggested to correspond to the inward rectifier and the H+ current of macrophages. |
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Keywords: | Microglia Macrophage colony-stimulating factor Patch clamp Whole-cell recording Inward rectifying potassium current Proton current |
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