THE INFLUENCE OF PLASMA MEMBRANE ION PERMEABILITY MODULATORS ON SUPEROXIDE FORMATION AND BIOELECTRICAL
CHARACTERISTICS OF WHEAT ROOT CELLS
V. Ya. Alekseeva, L. K. Gordon, O. P. Kolesnikov, A. N. Tsentsevitsky
Kazan' Institute of Biochemistry and Biophysics, Kazan' Research Center, RAS, Russia;
e-mail: alekseeva@mail.knc.ru
Changes in superoxide radical formation and bioelectrical characteristics of excised wheat root cells under
modification of plasma membrane ion permeability were studied. It was shown that a 2 h treatment of excised roots with
valinomycin (Val, 20 µÌ), N, N'-dicyclohexylcarbodimide (DCCD, 100 µÌ), gramicidin S (Gr, 20 µÌ), chlorpromazine
(CPZ, 100 µÌ) caused an increased loss of potassium by cells, lowering of membrane potential (MP) and electrical input
resistance (Rin) of the cells. The superoxide formation by excised root cells diminished (under DCCD) or
remained at the control level (under Val), which was accompanied by a minor decrease of MP and Rin of the cells, a small increase
in potassium loss by excised roots, and in no change of pH of incubation medium. Significant depolarization of plasma membrane,
dropping of Rin and essential loss of potassium ions by the cells correlated with a rise in the medium
alkalinization and superoxide formation by excised roots (in the presence of Gr, CPZ). Ion channel blocker gadolinium
(Gd3+, 200 µÌ) caused an increase of MP and Rin reduction of potassium loss by cells, and a
decrease of pH of the incubation medium, and also enhancement of superoxide formation by excised root cells. It is suggested
that upon plasma membrane ion permeability modification the activity of superoxide generating systems depends on the specificity
and mechanisms of action of modulators, and is determined by their influence on redox state of plasma membrane as well as by
peculiarities of ion transport disturbance.
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