Table 4.
Synopsis of Single-Channel Parameter Derived from HEK 293 Cells Transiently Transfected with Human CaV1.2 Isoforms α2δ1 and β2a
| Parameters/Splice Isoform | 1a/8 | 1a/8a | 1/8 | 1/8a | p-value |
|---|---|---|---|---|---|
| Availability (%) | 68 ± 10 (6) | 60 ± 7 (9) | 61 ± 9 (8) | 52 ± 11 (5) | p > 0.05 |
| Popen (%) | 4.1 ± 0.7 (6) | 3.0 ± 0.5 (9) | 6.0 ± 0.7 (8) | 4.2 ± 0.8 (5) | p > 0.05 |
| Iunitary (pA) | 0.82 ± 0.04 (6) | 0.88 ± 0.03 (9) | 0.78 ± 0.04 (8) | 0.79 ± 0.03 (5) | p > 0.05 |
| Ipeak (fA) | 48 ± 9 (6) | 48 ± 8 (9) | 46 ± 9 (8) | 53 ± 16 (5) | p > 0.05 |
| Mean open time (ms) | 0.44 ± 0.04 (6) | 0.35 ± 0.04 (8) | 0.35 ± 0.04 (8) | 0.36 ± 0.05 (5) | p > 0.05 |
| τopen (ms) | 0.32 ± 0.03(6) | 0.29 ± 0.03(8) | 0.29 ± 0.03(8) | 0.31 ± 0.04 (5) | p > 0.05 |
| Mean close time (ms) | 9.3 ± 2.7 (6) | 5.6 ± 1.4 (6) | 5.6 ± 1.4 (6) | 4.7 ± 1.9 (5) | p > 0.05 |
Unitary events were recorded with a 110-mM intracellular barium solution from cells held at a holding potential (HP) of −100 mV and pulsed to +10 mV for 150 ms. Parameters were idealized after semiautomatic leak subtraction with pClamp10. Mean open time and mean close time are given as arithmetic mean values. Tau values for mean close time could not be determined because of a too-small number of real single-channel events (n = 1). The fraction of active sweeps (availability) and open probability (Popen) were corrected according to the channel number (n). Iunitary was analyzed by visual estimation. The local extreme of the maximal peak (Ipeak) was derived from mean-ensemble average currents (>180 sweeps) after smoothening. The recorded cell number is given in parenthesis. Parameters are given as mean ± SE. A one-way ANOVA was used to determine statistical significance with a 0.05% confidence interval, p > 0.05.