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Interactions between NADPH oxidase‐related proton and electron currents in human eosinophils
Author(s) -
DeCoursey T. E.,
Cherny V. V.,
DeCoursey A. G.,
Xu W.,
Thomas L. L.
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.00767.x
Subject(s) - nadph oxidase , chemistry , superoxide , biophysics , respiratory burst , patch clamp , oxidase test , electrophysiology , stimulation , biochemistry , medicine , reactive oxygen species , endocrinology , enzyme , biology , receptor
1 Proton and electron currents in human eosinophils were studied using the permeabilized‐patch voltage‐clamp technique, with an applied NH 4 + gradient to control pH i . 2 Voltage‐gated proton channels in unstimulated human eosinophils studied with the permeabilized‐patch approach had properties similar to those reported in whole‐cell studies. 3 Superoxide anion (O 2 − ) release assessed by cytochrome c reduction was compared in human eosinophils and neutrophils stimulated by phorbol myristate acetate (PMA). PMA‐stimulated O 2 release was more transient and the maximum rate was three times greater in eosinophils. 4 In PMA‐activated eosinophils, the H + current amplitude ( I H ) at +60 mV increased 4.7‐fold, activation was 4.0 times faster, deactivation (tail current decay) was 5.4 times slower, the H + conductance‐voltage ( g H ‐ V ) relationship was shifted ‐43 mV, and diphenylene iodinium (DPI)‐inhibitable inward current reflecting electron flow through NADPH oxidase was activated. The data reveal that PMA activates the H + efflux during the respiratory burst by modulating the properties of H + channels, not simply as a result of NADPH oxidase activity. 5 The electrophysiological response of eosinophils to PMA resembled that reported in human neutrophils, but PMA activated larger proton and electron currents in eosinophils and the response was more transient. 6 ZnCl 2 slowed the activation of H + currents and shifted the g H ‐ V relationship to more positive voltages. These effects occurred at similar ZnCl 2 concentrations in eosinophils before and after PMA stimulation. These data are compatible with the existence of a single type of H + channel in eosinophils that is modulated during the respiratory burst.