title: Plasma membrane depolarization induced by abscisic acid in Arabidopsis suspension cells involves reduction of proton pumping in addition to anion channel activation, which are both Ca2+ dependent.
abstract: In Arabidopsis suspension cells a rapid plasma membrane depolarization is triggered by abscisic acid (ABA). Activation of anion channels was shown to be a component leading to this ABA-induced plasma membrane depolarization. Using experiments employing combined voltage clamping, continuous measurement of extracellular pH, we examined whether plasma membrane H(+)-ATPases could also be involved in the depolarization. We found that ABA causes simultaneously cell depolarization and medium alkalinization, the second effect being abolished when ABA is added in the presence of H+ pump inhibitors. Inhibition of the proton pump by ABA is thus a second component leading to the plasma membrane depolarization. The ABA-induced depolarization is therefore the result of two different processes: activation of anion channels and inhibition of H(+)-ATPases. These two processes are independent because impairing one did not suppress the depolarization. Both processes are however dependent on the [Ca2+]cyt increase induced by ABA since increase in [Ca(2+)](cyt) enhanced anion channels and impaired H(+)-ATPases.
authors.affiliation: Laboratoire d'Electrophysiologie des Membranes, EA 3514, Université Paris 7, 75251 Paris 05, France. brault@ccr.jussieu.fr
authors.forename: Mathias
authors.initials: M
authors.lastname: Brault
authors.forename: Zahia
authors.initials: Z
authors.lastname: Amiar
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Pennarun
authors.forename: Michèle
authors.initials: M
authors.lastname: Monestiez
authors.forename: Zongshen
authors.initials: Z
authors.lastname: Zhang
authors.forename: Daniel
authors.initials: D
authors.lastname: Cornel
authors.forename: Olivier
authors.initials: O
authors.lastname: Dellis
authors.forename: Heather
authors.initials: H
authors.lastname: Knight
authors.forename: François
authors.initials: F
authors.lastname: Bouteau
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Rona
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D010937:Plant Growth Regulators / Q000494:pharmacology; D054328:Proton Pump Inhibitors; D017494:Proton Pumps / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D007473:Ion Channels; D010937:Plant Growth Regulators; D054328:Proton Pump Inhibitors; D017494:Proton Pumps; D000040:Abscisic Acid; D006180:Proton-Translocating ATPases; D002118:Calcium