RAPID PRESSURE-DRIVEN EXOCYTOSIS ENDOCYTOSIS CYCLE IN A SINGLE PLANT-CELL - CAPACITANCE MEASUREMENTS IN ALEURONE PROTOPLASTS

The whole-cell patch-clamp technique has been used to increase intrace llular pressure via the pipette while monitoring changes in membrane c apacitance (related to membrane area) in single aleurone protoplasts. Increased pressure increased membrane capacitance and diameter, upon t he release of pressure both parameters returned to resting levels. Pre ssure also reversibly increased membrane conductance. Comparison betwe en diameter and capacitance shows that the rapacitance changes are due to changes in cell surface area. These results show that pressure can rapidly alter the balance between exo- and endocytosis. Pressure-indu ced changes in conductance are suggested to be due to insertion/withdr awal of channels with the exo-/endocytosed membrane.