title: K channels of human alveolar macrophages.
abstract: The activation of macrophages has been reported to be associated with Ca-activated K permeability change. In order to study this permeability change in human alveolar macrophages, we examined alveolar macrophages electrophysiologically at a single channel level. We observed two types of Ca-activated K channel currents having conductances of 218 +/- 2 and 32 +/- 0.6 picosiemens in symmetrical 154 mmol/L KCl solutions. The characteristics, such as voltage dependency and Ca sensitivity, as well as channel conductance, were different between these two types of channel currents. Quinine (a blocker of Ca-activated K conductance), 0.5 mmol/L, reduced these channel currents by 45 +/- 8% and 31 +/- 8%. Quinine, 0.5 mmol/L, also inhibited chemiluminescence and leukotriene B4 release by 82 +/- 6 to 88 +/- 3% and 88 +/- 2%, respectively. These results suggest the presence of two types of Ca-activated K channels, which may be related to the release of inflammatory mediators from human alveolar macrophages.
mesh_terms: D002118:Calcium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D006801:Humans; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007975:Leukotriene B4 / Q000378:metabolism; D008163:Luminescent Measurements; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000378:metabolism*; D011803:Quinine / Q000494:pharmacology; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
chemical_list: D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D007975:Leukotriene B4; D019789:Tetraethylammonium; D011803:Quinine; D011188:Potassium; D002118:Calcium