Figure 5. Single hCa_V3.3 channel currents are unaffected by T797M (T/M) and R1346H (R/H).

Recordings are from cell-attached patches from tsA201 cells transiently expressing WT, T/M and R/H hCa_V3.3. (a) Single WT hCa_V3.3 channel currents evoked by step depolarizations from −80 mV to −20 mV, upper panel. Ensemble current trace generated by adding multiple single channel traces recorded at −20 mV, lower panel; (b) Single hCa_V3.3 channel tail currents resolved immediately on membrane hyperpolarization to −50 mV from a depolarizing step to +60 mV (used to open the channels), upper panel. Tail currents are relatively large because of the large driving force at negative membrane potentials—although they close rapidly. Lower panel shows an ensemble tail current reconstructed from adding multiple single channel tail currents. Closed state is labeled (dotted line). (c) Average single Ca_V3.3 channel current amplitudes at different test potentials (TP, left panel) for each clone. Single channel conductances were estimated from slopes of single channel current (i)-voltage relationships (right panel). Mean ± SE, WT: 14.0 ± 0.8 pS (n = 8); T/M: 13.3 ± 0.27 pS (n = 3); and R/H: 13.7 ± 0.6 pS (n = 5). In each case, N corresponds to the number of individual patch recordings but each dataset represents measurements of >100 individual channel openings. Averages are shown with 99% confidence intervals calculated using bootstrap with resampling.