Reactive oxidants regulate membrane repolarization and store-operated uptake of calcium by formyl peptide-activated human neutrophils.
Although the rapid and considerable membrane depolarization response which accompanies activation of the phagocyte NADPH oxidase is due to transmembrane electron fluxes, little is known about the involvement of reactive oxidant species (ROS) in the subsequent repolarization response. In the current study, we have investigated the effects of superoxide dismutase (SOD), catalase, methionine, and the myeloperoxidase (MPO) inhibitors, sodium azide and 4-aminobenzoyl hydrazide (ABAH), as well as those of H(2)O(2) and HOCl (both at 100 microM) on the alterations in membrane potential which accompany activation of human neutrophils with the chemoattractant, FMLP (1 microM), and on store-operated uptake of Ca(2+). The generation of ROS by FMLP-activated neutrophils was monitored according to the magnitude of oxygen consumption and autoiodination, while spectrofluorimetric procedures were used to measure alterations in membrane potential and influx of Ca(2+). Treatment of the cells with H(2)O(2), and HOCl, significantly impeded membrane repolarization, while sodium azide, ABAH, methionine, and catalase exerted the opposite effects, potentiating both the rates and the magnitudes of membrane repolarization and store-operated uptake of Ca(2+). These observations demonstrate that NADPH oxidase regulates neutrophil membrane potential and Ca(2+) influx not only via its electrogenic activity, but also as a consequence of the generation of ROS.
Tintinger
Gregory R
GR
Department of Internal Medicine, Faculty of Health Sciences, University of Pretoria, South Africa.
Theron
Annette J
AJ
Potjo
Moliehi
M
Anderson
Ronald
R
D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002630:Chemotactic Factors / Q000494:pharmacology*; D016257:Fura-2 / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006997:Hypochlorous Acid / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects*; D008715:Methionine / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D019255:NADPH Oxidases / Q000378:metabolism; D018375:Neutrophil Activation / Q000187:drug effects*; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects; D009195:Peroxidase / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D019810:Sodium Azide / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology
D015220:Calcium Channels; D002630:Chemotactic Factors; D016877:Oxidants; D017382:Reactive Oxygen Species; D008345:Manganese; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019284:Thapsigargin; D006997:Hypochlorous Acid; D000255:Adenosine Triphosphate; D019810:Sodium Azide; D008715:Methionine; D006861:Hydrogen Peroxide; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase; D019255:NADPH Oxidases; D002118:Calcium; D016257:Fura-2