A METHOD OF RESOLUTION IMPROVEMENT BY THE MEASUREMENT OF CELL-MEMBRANE CAPACITANCE

When measuring cell membrane electrical capacitance in whole cell conf iguration using alternating currents, the resolution decreases with in creasing membrane conductance and pipette resistance. Improved resolut ion was attained by the dual-frequency method which was modified as to control the voltage amplitude of one of the measuring frequencies. A model circuit was developed for the verification of the method This ci rcuit allows measurement of calibrated capacitance changes even in the range of 5 to 20 fF. Moreover, the method was applied to capacitance measurements on pancreatic exocrine acinar cells. The results of measu rements on the model as well as on pancreatic acinar cells are present ed. The principle can also be applied to other hardware and software m ethods for measuring electrical cell membrane parameters.