Data di Pubblicazione:
2002
Citazione:
Membrane depolarization induces K+ efflux from subapical maize root segments / F.F. Nocito, G.A. Sacchi, M. Cocucci. - In: NEW PHYTOLOGIST. - ISSN 0028-646X. - 154:1(2002), pp. 45-51. [10.1046/j.1469-8137.2002.00369.x]
Abstract:
•The role of potassium efflux from maize (Zea mays) root segments in maintaining transmembrane electric potential difference (Em) was studied
in vivo, together with the involvement of outward rectifying K+ channels (ORCs).
•Measurements were made of the efflux of potassium (K+) from roots when its
uptake was competitively inhibited by rubidium (Rb+), of the Em of the root cells by microelectrodes and of the unidirectional fluxes of monovalent cations.
•The influx of Rb+, caesium (Cs+) or ammonium (NH4+) into the segments induced an efflux of K+. Lithium (Li+) and sodium (Na+) were not taken up and did not induce K+efflux. The permeating cations induced membrane depolarizations, which were closely related to the values of K+ efflux. Two K+-channel blockers, tetraethylammoniumchloride and quinidine, inhibited K+ efflux. The inhibition was accompanied by a higher
membrane depolarization induced by Rb+, whose influx was not affected.
•The results suggest that a depolarizing event caused by cation uptake increased K+ efflux from the cells, probably through the activation of ORCs involved in restoration and stabilization of Em.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
potassium channels ; potassium efflux ; stabilization of Em ; Zea mays
Elenco autori:
F.F. Nocito, G.A. Sacchi, M. Cocucci
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