Modulation of I Cl(Ca) in vascular smooth muscle cells by oxidizing and cysteine-reactive reagents

• Published in: Pflügers Archiv Vol. 443; no. 3; pp. 473 - 482
• Main Authors: Greenwood, Iain A., Leblanc, Normand, Gordienko, Dmitri V., Large, William A.
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01.01.2002
• ISSN: 0031-6768; 1432-2013
• DOI: 10.1007/s004240100709

The present study investigated the effect of redox agents on Ca^sup 2+^-activated Cl^sup -^ currents (I ^sub Cl(Ca)^) recorded in smooth muscle cells isolated from rabbit portal vein. In perforated-patch experiments on portal vein cells the amplitude of I ^sub Cl(Ca)^ evoked by either spontaneous release of Ca^sup 2+^ from internal stores or Ca^sup 2+^ influx through voltage-dependent Ca^sup 2+^ 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 ^sub Cl(Ca)^ but reversed the increase of current amplitude produced by diamide. Diamide also increased global intracellular Ca^sup 2+^ 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 ^sub Cl(Ca)^evoked by pipette solutions containing free Ca^sup 2+^ 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 Ca^sup 2+^-activated Cl^sup -^ conductance is sensitive to redox modification.[PUBLICATION ABSTRACT]