K outward rectifying channels as targets of phosphatase inhibitor deltamethrin inVicia faba guard cells |
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Authors: | Ferenc Horvth Lszl Erdei Barnabs Wodala Ulrike Homann Gerhard Thiel |
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Institution: | Ferenc Horváth, László Erdei, Barnabás Wodala, Ulrike Homann,Gerhard Thiel |
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Abstract: | The dominant outward rectifier K+ currents were examined in protoplasts from Vicia faba guard cells. In whole-cell patch-clamp recordings, we generally observed that the conductance of the K+ inward and the outward rectifier gradually decreases with a half time in the order of 2.3 ± 0.7 min. As a consequence of this rundown, a new steady state was achieved which was 90 ± 5 percnt; lower than that obtained at the beginning of the recording. The rundown of the outward rectifier could be greatly reduced by pre-treating protoplasts either with the membrane permeable drug deltamethrin or by perfusing protoplasts with a pipette solution containing 5 μmol/L cyclosporine A. Furthermore, after the rundown, the conductance of the outward rectifier could be partially restored upon addition of 5 μmol/L deltamethrin to the bath medium. Since deltamethrin and cyclosporine A are established inhibitors of the calcium sensitive phosphatase calcineurin, the data argue for a participation of this type of phosphatase in the control of the activity of K+ outward rectifier channels in guard cells. |
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Keywords: | Vicia faba deltamethrin guard cell calcineurin K+ outward rectifier rundown |
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