Calcium- and voltage-activated potassium channels in human macrophages

Abstract

Single calcium-activated potassium channel currents were recorded in intact and excised membrane patches from cultured human macrophages. Channel conductance was 240 pS in symmetrical 145 mM K+ and 130 pS in 5 mM external K+. Lower conductance current fluctuations (40% of the larger channels) with the same reversal potential as the higher conductance channels were noted in some patches. Ion substitution experiments indicated that the channel is permeable to potassium and relatively impermeable to sodium. The frequency of channel opening increased with depolarization and intracellular calcium concentration. At 10(-7) M (Ca++)i, channel activity was evident only at potentials of +40 mV or more depolarized, while at 10(-5) M, channels were open at all voltages tested (-40 to +60 mV). In intact patches, channels were seen at depolarized patch potentials of +50 mV or greater, indicating that the ionized calcium concentration in the macrophage is probably less than 10(-7) M.

Modulation of Voltage-Dependent and Inward Rectifier Potassium Channels by 15-Epi-Lipoxin-A4 in Activated Murine Macrophages: Implications in Innate Immunity

“…Moreover, several groups have reported the expression of K v 1.3 in macrophages and microglia (5,16,(43)(44)(45)(46)(47)(48), and our data add new insights on the fine-tuning of these channels by lipoxins. Indeed, K v 1.3 channels, together with K ir 2.1, K v 1.5, K Ca 3.1, and BK Ca channels, modulate macrophage and microglia function, and, at the same time, pharmacological channel blockers may have effects on the immune response (5,44,49,50).…”

The voltage-gated potassium channel Kv1.3 is highly expressed on inflammatory infiltrates in multiple sclerosis brain

“…Kv1.3 channels are required only for the later stages of proliferation of rodent microglia, whereas Kv1.5 channels are necessary during the early stages (36). Other studies suggest that Kv1.3 channels, together with Kir2.1, Kv1.5, KCa3.1, and BK Ca channels, modulate macrophage and microglia function (35,38,(41)(42)(43). Kv1.3 blockers may therefore have effects on chronically activated T EM cells, and may also partially influence the function of microglia and brain macrophages.…”

Differential Voltage-dependent K+ Channel Responses during Proliferation and Activation in Macrophages

“…RT-PCR was set as described under "Experimental Procedures" with oligonucleotides from Kv1.1 (accession number NM_010595; base pairs 1102-1807), Kv1.2 (accession number NM_008417, base pairs 841-1691), Kv1.5 (accession number AF302768, base pairs 3003-3337), Kv1.6 (accession number NM_013568, base pairs 233-1822), and Kv3.1 (accession number Y07521, base pairs 727-1231). Lanes 1,3,5,7,9, and 10, PCR reactions from BMDM. Lanes 2,4,6,8,11, PCR from mouse brain.…”