| Popis: |
Data on the NO3 − accumulation mechanisms at the tonoplast has remained widely unknown. NO3 − uptake induced a depolarization or an hyperpolarization of cells (Ullrich and Novacky, 1981; Thibaud and Grignon, 1981). This can be classically attributed to an electrogenic 0H−/NO3 − antiport or H+/NO3 − symport at the plasmalemma (Rona and Cornel, 1984; Thibaud and Grignon, 1981). But the existence of an NO3inhibited and Cl−-stimulated Mg-ATPase on tonoplast is now well established (Sze, 1985). Furthermore, NO3 − vacuolar net accumulation could give rise to depolarization of the tonoplastic membrane. Nitrate induced hyperpolarization in cells could result partly from the depolarization of the tonoplast. The aim of these experiments was to investigate some of the NO3 − vacuolar uptake characteristics and those of related electrical events. |
