Brault Mathias, Amiar Zahia, Pennarun Anne-Marie, Monestiez Michèle, Zhang Zongshen, Cornel Daniel, Dellis Olivier, Knight Heather, Bouteau François, Rona Jean-Pierre
Laboratoire d'Electrophysiologie des Membranes, EA 3514, Université Paris 7, 75251 Paris 05, France.
Plant Physiol. 2004 May;135(1):231-43. doi: 10.1104/pp.104.039255.
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+) enhanced anion channels and impaired H(+)-ATPases.
在拟南芥悬浮细胞中，脱落酸（ABA）可引发质膜快速去极化。阴离子通道的激活被证明是导致这种ABA诱导的质膜去极化的一个因素。通过采用联合电压钳制、连续测量细胞外pH值的实验，我们研究了质膜H(+) - ATP酶是否也参与去极化过程。我们发现，ABA同时引起细胞去极化和培养基碱化，当在H+泵抑制剂存在的情况下添加ABA时，第二个效应被消除。因此，ABA对质子泵的抑制是导致质膜去极化的第二个因素。因此，ABA诱导的去极化是两个不同过程的结果：阴离子通道的激活和H(+) - ATP酶的抑制。这两个过程是独立的，因为损害其中一个并不会抑制去极化。然而，这两个过程都依赖于ABA诱导的[Ca2+]cyt增加，因为Ca(2+)的增加增强了阴离子通道并损害了H(+) - ATP酶。
