Phorbol 12-myristate 13-acetate activates an electrogenic H(+)-conducting pathway in the membrane of neutrophils.
The mode of activation of an H(+)-conducting pathway present in the membrane of neutrophils was investigated. (1) Resting neutrophils released protons through an electrogenic Cd(2+)-inhibitable (K0.5 approximately 20 microM) route when a pH gradient and appropriate charge compensation was provided. (2) The rate of H+ efflux was stimulated over 2.5-fold by 4 beta-phorbol 12-myristate 13-acetate (PMA; K0.5 approximately 0.7 nM) or by 4 beta-phorbol 12,13-dibutyrate (K0.5 approximately 20 nM) even when the NADPH oxidase was blocked by p-chloromercuribenzoate. (3) Staurosporine inhibited the effect of PMA. (4) The H+ egress was not enhanced by 4 alpha-phorbol 12,13-didecanoate. (5) Low concentrations of Cd2+ (less than 40 microM) inhibited the H+ flux without influencing the oxidase. The results raise the possibility that protein kinase C could be involved in the activation of an electrogenic H(+)-conducting pathway in the membrane of neutrophils. The activation of this route by phorbol esters seems to be independent of the stimulation of NADPH oxidase.
Department of Physiology, Semmelweis University Medical School, Budapest, Hungary.
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Kapus
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Szászi
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Ligeti
D000818:Animals; D001692:Biological Transport; D002104:Cadmium / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology*; D002463:Cell Membrane Permeability; D002729:Chloromercuribenzoates / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019255:NADPH Oxidases; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011522:Protons; D013552:Swine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014634:Valinomycin / Q000494:pharmacology; D020245:p-Chloromercuribenzoic Acid
D002729:Chloromercuribenzoates; D007473:Ion Channels; D011522:Protons; D002104:Cadmium; D014634:Valinomycin; D015240:Phorbol 12,13-Dibutyrate; D020245:p-Chloromercuribenzoic Acid; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate