IONIC TRANSPORT IN THE PLASMA-MEMBRANE OF CARROT PROTOPLASTS FROM EMBRYOGENIC CELL-SUSPENSION CULTURES

Ionic transport properties of protoplasts obtained from embryogenic ca rrot suspension cells were studied by the patch-clamp technique, In th e whole-cell configuration, carrot protoplasts presented macroscopic t ime-dependent outward currents, showing kinetics of activation which d id not depend appreciably on the amplitude of the stimulus, time- and voltage-dependent whole-cell in inward rectifying currents as well as instantaneous non-selective currents were also observed, Both time-dep endent inward and outward currents are carried by potassium ions. In a cell-attached configuration, two types of single-channel signals, dis playing conductances of 10 and 17 pS, were observed; the instantaneous 10 pS channel was also present in outside-out excised patches.