A, capacitance trace (fF) and amperometric current (pA) simultaneously recorded in a control cell infected with the GFP–IRES–β-galactosidase adenovirus. The voltage protocol, 20 depolarizations, −90 mV to +20 mV, 200 ms intervals, is displayed below the amperometric trace. B, simultaneous capacitance and amperometric recordings in a cell infected with the Rab3AQ81L–IRES–GFP adenovirus.