Effects of Cr on proton extrusion,potassium uptake and transmembrane electric potential in maize root segments
Articolo
Data di Pubblicazione:
1985
Citazione:
Effects of Cr on proton extrusion,potassium uptake and transmembrane electric potential in maize root segments / P. Zaccheo, M. Cocucci, S. Cocucci. - In: PLANT, CELL AND ENVIRONMENT. - ISSN 0140-7791. - 8:9(1985), pp. 721-726.
Abstract:
Abstract Proton extrusion of maize root Zea mays segments, was inhibited by the presence of Cr (o.n. + 6; present in solution as CrO42‐, Cr2O72‐) in the incubation medium: the minimum inhibiting concentration was 2 × 10−3 mol m−3 and the inhibition progressively increased with Cr concentration. Cr inhibited proton extrusion. Also, when this activity was stimulated by the presence of K+ or fusicoccin (FC) in the incubation medium, the K+ and FC stimulating effect was still present when proton extrusion was inhibited by Cr. In addition, Cr inhibited K+ uptake. This inhibition was higher (50%) at K+ concentrations up to 1 mol m−3 lower (15%) at higher K+ concentrations. This result indicates that the system responsible for K+ uptake operating at low K+ concentrations is more sensitive to Cr inhibition. Cr had no effect on transmembrane electric potential (PD). The depolarizing and hyper‐polarizing effect of K+ and FC, respectively, were not affected by Cr; but Cr enhances the depolarizing effect of the uncoupler carbonylcyanide m‐chlorophenylhydrazone (CCP). These results indicate that Cr inhibited the proton translocating mechanism coupled with K+ uptake, but did not change the net transport of charges through the plasmalemma. The Cr effect is discussed, taking into account the possibility of a direct effect of Cr at the membrane level or, alternatively, of an effect on some metabolic processes controlling membrane function.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
P. Zaccheo, M. Cocucci, S. Cocucci
Link alla scheda completa: