Figure 2.

Typical C_m measurement in chromaffin cells in slices. (A) Capacitance increase in response to a 10 ms long depolarization from the holding potential of −80 mV to 0 mV (center), which is flanked by preceding and after control measurements (no depolarization). After the depolarization the capacitance exhibits a decaying transient (ΔC_t) in addition to the stable elevation. The measuring sweeps were separated by 1–3 s (intervals indicated by dashed lines). The dc voltage protocol is displayed in the uppermost panel with the 10-ms constant voltage segments indicated by bold bars. Test and control ΔC_m values were estimated as the differences between C_m averages taken over the shaded time window after the constant voltage segments (long) with respect to averages over the preceding shaded window (short). (B and C) Membrane conductance (G_m) and series resistance (G_s) are shown to illustrate that there was no major crosstalk between C_m, G_m, and G_s lock-in estimates.