Large-conductance calcium-activated potassium channel activity is absent in human and mouse neutrophils and is not required for innate immunity

Item Type:	Article
Title:	Large-conductance calcium-activated potassium channel activity is absent in human and mouse neutrophils and is not required for innate immunity
Creators Name:	Essin, K. and Salanova, B. and Kettritz, R. and Sausbier, M. and Luft, F.C. and Kraus, D. and Bohn, E. and Autenrieth, I. and Peschel, A. and Ruth, P. and Gollasch, M.
Abstract:	Large-conductance calcium-activated potassium (BK) channels are reported to be essential for NADPH oxidase-dependent microbial killing and innate immunity in leukocytes. We studied this issue using human peripheral blood and mouse bone marrow neutrophils, pharmacological targeting, and BK channel gene-deficient (BK-/-) mice. We stimulated NADPH oxidase activity using 12-O-tetradecanoylphorbol-13-acetate (PMA) and performed patch clamp recordings on isolated neutrophils. Although PMA stimulated NADPH oxidase activity as assessed by O2(-) and H2O2 production, our patch clamp experiments failed to show BK channel currents activated by PMA in neutrophils. In our studies, PMA induced slowly activating currents, which were insensitive to the BK channel inhibitor iberiotoxin. Instead, the currents were blocked by Zn(2+), which indicates activation of proton channel currents. BK channels are gated by both elevated intracellular Ca(2+) levels and membrane depolarization. We did not observe BK channel currents, even during extreme depolarization to +140mV and after elevation of intracellular [Ca(2+)] by N-formyl-L-methionyl-L-leucyl-phenylalanine (fMLP). As a control, we examined BK currents in cerebral and tibial artery smooth muscle cells, which showed characteristic BK channel current pharmacology. Iberiotoxin did not block killing of S.aureus or C.albicans. Moreover, we addressed the role of BK channels in a systemic S.aureus and Y.enterocolitica mouse infection model. After 3 and 5 days of infection, we found no differences in the bacterial numbers in the spleen and kidney between BK-/- and BK+/+ mice. In conclusion, our experiments failed to identify functional BK channels in neutrophils. We therefore conclude that BK channels are not essential for innate immunity. Key words: potassium channel, killing assay, reactive oxygen species, BK-deficient mice, mice infection.
Keywords:	Potassium channel, Killing assay, Reactive oxygen species, BK-deficient mice, Mice infection, Animals, Mice
Source:	American Journal of Physiology Cell Physiology
ISSN:	0363-6143
Publisher:	American Physiological Society
Volume:	293
Number:	1
Page Range:	C45-C54
Date:	11 July 2007
Official Publication:	https://doi.org/10.1152/ajpcell.00450.2006
PubMed:	View item in PubMed

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