Procedure 2: Calculation of the membrane resistance (Rm)
Cells were held at -60 mV in voltage-clamp mode. Ten steps to -65 mV (1s
duration @ 1 Hz) were generated and recorded on fifteen separate
electrophysiological traces and a median trace was calculated. The Rm
was calculated on the median trace according to ohm’s low R=ΔV/ΔI where
ΔV=-5mV and ΔI was the difference between the median current in the last
100 ms of the hyperpolarization and the median current in the 200 ms
pre-step period. Access resistance AR was calculated as
AR=ΔV/ΔIA where ΔIA is
the difference between the peak of transient current and the median
current in the 200 ms pre-step period.