Abscisic Acid-Induced Membrane Potential Changes in Barley Aleurone Protoplasts : a Possible Relevance for the Regulation of rab Gene Expression : MEMBRANES AND BIOENERGETICS

概要

論文の詳細を見る
The effect of ABA on the membrane potential of barley (Hordeum vulgare cv. Himalaya) aleurone protoplasts was studied by measuring the distribution of the lipophilic cation tetraphenylphosphonium (TPP^+). The resting membrane potential (E_m) according to our measurements with TPP^+ is about -53 mV and is in agreement with membrane potential values as measured with intracellular microelectrodes (about -55 mV). The TPP^+-measurements could demonstrate a clear dependence of the resting E_m on the external pH (pH_e). Stimulation of the protoplasts with ABA induced a transient hyperpolarization of the membrane to -62 mV as measured with TPP^+. The hyperpolarization was ABA-concentration dependent. Inhibition of the H^+-ATPases with the specific proton pump inhibitors diethylstilbestrol (DES) or Micanozole effectively prevented hyperpolarization. This indicates that the hyperpolarization is consistent with the activation of plasma membrane H^+-ATPases. The K^+-inward rectifier inhibitor BaCl_2 was able to prolong the hyperpolarization. This result suggests that the hyperpolarization causes the opening of K^+-channels. The ABA-induced proton-pump activation may be involved in ABA-induced gene-expression, as DES was able to inhibit this gene expression. BaCl_2 did only show a slight inhibitory effect on ABA-induced gene-expression.
日本植物生理学会の論文