Table 1.
Biophysical parameters of Cav3.1 channel variants expressed in HEK-293T cells.
| Variant \\ Biophysical Property |
Wild-Type | L208P | L909F | M1508V |
|---|---|---|---|---|
| Current density (pA/pF) n |
206.9 ± 36.2 (15) 15 |
180.5 ± 37.4 (13) 13 |
275.2 ± 40.8 (15) 15 |
261.5 ± 46.9 (9) 9 |
| Activation V0.5,act (mV) kact (mV) n |
−31.27 ± 0.44 5.33 ± 0.21 15 |
−41.66 ± 0.50 **** 5.56 ± 0.31 13 |
−35.72 ± 0.60 ****5.04 ± 0.2515 |
−43.68 ± 0.12 **** 4.81 ± 0.11 9 |
| Inactivation V0.5,inact (mV) kinact (mV) n |
−61.18 ± 1.01 5.84 ± 0.42 8 |
−67.93 ± 0.47 **** 6.50 ± 0.41 7 |
−62.43 ± 0.24 6.01 ± 0.31 9 |
−66.63 ± 0.33 **** 6.27 ± 0.29 7 |
| Activation kinetics τ at −50 mV (ms) τ at −30 mV (ms) n |
7.49 ± 0.73 4.72 ± 0.35 15 |
24.40 ± 2.35 **** 5.60 ± 0.44 13 |
8.84 ± 1.14 4.03 ± 0.28 15 |
16.58 ± 0.58 **** 2.99 ± 0.16 9 |
| Inactivation kinetics τ at −50 mV (ms) τ at −10 mV (ms) n |
138.49 ± 14.62 13.56 ± 0.58 15 |
227.32 ± 22.0 **** 81.90 ± 5.4 **** 13 |
126.20 ± 11.0 13.07 ± 0.59 15 |
114.91 ± 15.6 41.16 ± 3.8 ** 9 |
| Deactivation kineticsτ at −70 mV (ms)τ at −50 mV (ms)n |
3.11 ± 0.10 6.21 ± 0.27 6 |
33.55 ± 5.54 **** 80.04 ± 6.58 **** 6 |
5.66 ± 0.35 **** 11.6 ± 0.76 **** 7 |
21.91 ± 2.30 ** 46.72 ± 2.80 **** 6 |
| Recovery§ τf (ms) Af (ms) τs (ms) As (ms) n |
66.52 ± 8.7 0.79 ± 0.07 450.03 ± 117.6 0.21 ± 0.07 9 |
299.82 ± 70.6 **** 0.61 ± 0.09 4904.4 ± 1608 *** 0.36 ± 0.06 6 |
61.05 ± 5.0 0.74 ± 0.04 492.28 ± 109.8 0.27 ± 0.04 9 |
112.18 ± 18.5 0.76 ± 0.12 534.03 ± 236 0.26 ± 0.13 5 |
| Current availability 1 Hz, 10th stimulus (%)− 1 Hz, 60th stimulus (%)− 3 Hz, 30th stimulus (%)− 3 Hz, 180th stimulus (%)− n |
0.969 ± 0.01 0.864 ± 0.03 0.835 ± 0.03 0.635 ± 0.06 8 |
0.597 ± 0.05 **** 0.335 ± 0.03 **** 0.205 ± 0.03 **** 0.125 ± 0.01 **** 8 |
0.958 ± 0.03 0.829 ± 0.04 0.695 ± 0.02 ** 0.382 ± 0.04 **** 8 |
0.859 ± 0.02 * 0.514 ± 0.05 **** 0.437 ± 0.06 **** 0.221 ± 0.02 **** 5 |
Data are represented as mean ± SEM; n, number of experiments, V0.5,(in)act, membrane potential for half-maximal (in)activation; k(in)act, slope factor of steady-state (in)activation curve; tf and ts, fast and slow recovery time constants, respectively; Af and As, fractions of fast and slow recovery from inactivation, recovery§, recovery from fast inactivation. Two-way ANOVA with Dunnett’s multiple comparison test was used to statistically evaluate ‘current density’; time constants of activation, inactivation, and deactivation; and peak current amplitudes during 1- and 3-Hz depolarizations. One-way ANOVA with Dunnett’s multiple comparison test was used to evaluate the parameters of (in)activation (V0.5,(in)act, k(in)act) and recovery (tf, ts, Af, and As). Note that the M1508V and L208P mutations cause similar changes of the V0.5,(in)act values, time course of (in)activation, deactivation kinetics, and current availability relative to WT whereas the L909F mutation affects a smaller number of biophysical parameters relative to wild-type; Asterisks indicate statistically significant differences using one-way ANOVA or two-way ANOVA followed by Dunnett’s multiple comparison test; * p < 0.05, ** p < 0.01, *** p < 0.001, or **** p < 0.0001 compared with wild type.