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Oxidized glutathione mediates cation channel activation in calf vascular endothelial cells during oxidant stress.
Author(s) -
Koliwad S K,
Elliott S J,
Kunze D L
Publication year - 1996
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 - 10.1113/jphysiol.1996.sp021572
Subject(s) - chemistry , glutathione , depolarization , membrane potential , biophysics , glutathione disulfide , patch clamp , oxidative stress , intracellular , redox , biochemistry , cytosol , enzyme , inorganic chemistry , biology , receptor
1. The oxidant, tert‐butylhydroperoxide (tBuOOH) depolarizes calf pulmonary artery endothelial cells by activating a non‐selective cation channel. To identify the molecular mediator of channel activation during oxidant stress, the patch‐clamp technique was used to compare tBuOOH‐induced changes in membrane potential and channel activity with those induced by oxidized glutathione (GSSG), a cytosolic product of oxidant metabolism. 2. When recording pipettes contained GSSG (2 mM), whole‐cell zero‐current potential measured immediately following pipette break‐in was not different from control values (‐57 mV). However, within 20 min of break‐in, zero‐current potential was depolarized to ‐7 mV. The time course of depolarization was dependent on the concentration of GSSG and was accelerated by inhibition of GSSG metabolism. 3. In excised membrane patches, channels were activated by internal GSSG, but not by internal tBuOOH, reduced glutathione (GSH), or external GSSG. Channels were equal in size (28 pS) and in ionic selectivity to those activated by incubation of intact cells with tBuOOH. As little as 20 microM GSSG was sufficient to maximally activate channels. However, the time course of channel activation was concentration dependent between 20 microM and 2 mM GSSG. 4. Channel activation by GSSG was reversed by GSH and by increasing the [GSH]:[GSSG] ratio. Likewise, channel activation by pre‐incubation of intact cells with tBuOOH was reversed by GSH applied after patch excision. 5. These results strongly suggest that GSSG is an endogenous intracellular mediator of channel activation and depolarization during oxidant stress.