Electrical characteristics of the tonoplast of cham corallincr. A study using permeabilised cells

Use of permeabilised cells of Chara corallina provides a unique opportunity to study the electrical characteristics of the tonoplast whilst being able to control ionic conditions on the outside of the membrane. Current-voltage (I/V) analysis over wide voltage spans, and admittance measurements at 5 Hz showed that many permeabilised cells had a similar conductance and capacitance to the tonoplast of intact cells. Cells developed two regions of negative-slope conductance upon addition of external Cl^-, which suggests the existence of potential-dependent Cl^- channels in the Chara tonoplast. With Cl^- concentrations similar to those expected in vivo, the resting potential was more sensitive to changes in external K⁺ than Cl^-; however, a decrease in external K⁺ did not significantly alter the shape of the I/V relation.