Induction of nitric oxide and respiratory burst response in activated goldfish macrophages requires potassium channel activity.
Potassium channel activity is important for modulating mammalian macrophage antimicrobial functions. The involvement of potassium channels in mediation of immune cell function in lower vertebrates, such as teleost, has not been explored. Since relatively little is known about the types of potassium channels present in fish macrophages, pharmacological blockers with broad ranges of activity were tested: 4-aminopyridine (4-AP), quinine, and tetraethylammonium chloride (TEA). The potassium channel blockers inhibited reactive nitrogen intermediates (RNI) and reactive oxygen intermediates (ROI) production by goldfish macrophages activated with bacterial lipopolysaccharide (LPS) and/or macrophage activating factor (MAF)-containing supernatants. Quinine was the most potent inhibitor with an IC(50) of 50 microM, while the other blockers, 4-AP and TEA, had IC(50) of 1.2 and 0.6mM, respectively. A reversible depolarization of the goldfish macrophage plasma membrane potential (Vm) was observed following treatments with potassium channel blockers, and was related to transcriptional changes in the inducible nitric oxide synthase gene (iNOS). Down-regulation of antimicrobial activities and depolarization of the goldfish macrophage plasma membrane were not a consequence of reduced cell number or viability, suggesting that potassium channels are required for generation of appropriate goldfish macrophage antimicrobial functions.
Stafford
James L
JL
Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, Alta., Canada T6G 2E9.
Galvez
Fernando
F
Goss
Gregory G
GG
Belosevic
Miodrag
M
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D006054:Goldfish / Q000276:immunology*; D008262:Macrophage Activation / Q000187:drug effects / Q000502:physiology*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000276:immunology; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000276:immunology*; D011803:Quinine / Q000494:pharmacology; D016897:Respiratory Burst / Q000187:drug effects / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019789:Tetraethylammonium / Q000494:pharmacology
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D009569:Nitric Oxide; D019789:Tetraethylammonium; D011803:Quinine; D015761:4-Aminopyridine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II