Ion Transport in Isolated Protoplasts from Tobacco Suspension Cells: II. Selectivity and Kinetics.

Protoplasts were enzymically isolated from suspension cultured cells of Nicotiana glutinosa L. and aspects of transport selectivity and kinetics were studied. In the presence of Ca(2+), transport was selective for K(+) ((86)Rb) over Na(+). (36)Cl(-) transport was inhibited by Br(-) or I(-) but not by H(2)PO(4) (-). The kinetic data for short term (30 minutes) K(+) influx over the range of 0.05 to 100 millimolar KCl were complex but similar to those observed in other plant tissues. In contrast, the kinetic data for Cl(-) and H(2) (32)PO(4) (-) over the same concentration range were different from those observed for K(+), and could be accounted for by a single isotherm in the range of 0.05 to 4 millimolar and by an almost linear increase in influx rate above 4 millimolar. The kinetic data for Cl(-) transport into intact cultured cells were identical in character to those observed for isolated protoplasts. The results support the view that enzymic removal of the cell wall produced no significant alteration in the transport properties of the protoplast.