Table I.
Permeation of various anions (x) through the quickly activating anion conductance in the plasma membrane of protoplasts isolated from maize stelar parenchyma (Zm-X-QUAC), measured by reversal potentials in biionic solutions, and inward currents and conductances
All experiments were conducted with 50 mM Cl− in the pipette (solution ISC) and external solutions ESN, ESA, ESI, ESK, ESM, and ESL (running from top to bottom) with the maintenance of at least 0.1 mm Ca2+. Ix/ICl− was calculated for currents at +120 mV. Gx/GCl− was calculated from the chord conductance from Erev to 60 mV positive of Erev. Values are the average of two measurements.
| [Anion] in the Bath | Reversal Potential | Ix/ICl− | Gx/GCl− | |
|---|---|---|---|---|
| mM | mV | |||
| Nitrate | 20 NO3− | 3.8 | 1.7 | 1.0 |
| Chloride | 20 Cl− | 32.5 | 1.0 | 1.0 |
| Iodide | 20 I− | 64.0 | 0.94 | 0.59 |
| Sulfate | 10 SO42− | 82.8 | 0.11 | 0.12 |
| Malate | 10 C4H6O42− | 82.6 | 0.02 | 0.18 |
| Citrate | 6.6 C6H5O73− | 100.3 | 0.01 | 0.10 |