Abstract
The present study investigated the effect of redox agents on Ca2+-activated Cl– currents (I Cl(Ca)) recorded in smooth muscle cells isolated from rabbit portal vein. In perforated-patch experiments on portal vein cells the amplitude of I Cl(Ca) evoked by either spontaneous release of Ca2+ from internal stores or Ca2+ influx through voltage-dependent Ca2+ channels was markedly and irreversibly enhanced by the non-specific oxidant, diamide (10–200 µM). Diamide also prolonged the decay of both currents. The reductant dithiothreitol had no effect on control I Cl(Ca) but reversed the increase of current amplitude produced by diamide. Diamide also increased global intracellular Ca2+ at rest but had no effect on the time-course of Ca "sparks" determined by confocal microscopy. Diamide and the endogenous oxidant hydrogen peroxide increased the amplitude and prolonged the kinetics of I Cl(Ca) evoked by pipette solutions containing free Ca2+ clamped at 500 nM. Similar effects were observed with the hydrophilic thiol-reactants thimerosal and p-chloromercuriphenylsulphonic acid (PCMPS). Therefore, the gating and activation of Ca2+-activated Cl– conductance is sensitive to redox modification.
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Greenwood, I.A., Leblanc, N., Gordienko, D.V. et al. Modulation of I Cl(Ca) in vascular smooth muscle cells by oxidizing and cysteine-reactive reagents. Pflügers Arch - Eur J Physiol 443, 473–482 (2002). https://doi.org/10.1007/s004240100709
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DOI: https://doi.org/10.1007/s004240100709