Table 1.
Biophysical properties of newly generated stable cell lines expressing hCav1.3L, hCav1.3S, or hCav1.2 together with human β3 and α2δ1 (2 mm Ca2+)
| 2 mm Ca2+ | V0.5 (mV) | k (mV) | Act thresh (mV) | V0.5,inact (mV) | kinact (mV) | Plateau (%) | r100 (%) | r250 (%) | r5000 (%) | n |
|---|---|---|---|---|---|---|---|---|---|---|
| Voltage dependence of activation | ||||||||||
| hCav1.3L | −27.7 ± 0.3 | 7.2 ± 0.1 | −54.2 ± 0.3 | 134 | ||||||
| hCav1.3S | −34.9 ± 0.3*** | 6.0 ± 0.1*** | −56.3 ± 0.3*** | 167 | ||||||
| hCav1.2 | −11.0 ± 0.2***,+++ | 6.9 ± 0.1***,+++ | −36.3 ± 0.2***,+++ | 121 | ||||||
| Voltage dependence of inactivation | ||||||||||
| hCav1.3L | −49.5 ± 1.2 | 4.8 ± 0.2 | 9.5 ± 1.2 | 15 | ||||||
| hCav1.3S | −52.7 ± 0.8* | 4.1 ± 0.2* | 3.7 ± 0.5*** | 18 | ||||||
| hCav1.2 | −37.3 ± 0.6***,+++ | 5.4 ± 0.2+++ | 5.6 ± 1.0* | 13 | ||||||
| 5 s inactivation | ||||||||||
| hCav1.3L | 35.6 ± 1.8 | 20.5 ± 1.5 | 6.1 ± 0.9 | 17 | ||||||
| hCav1.3S | 17.0 ± 0.9*** | 9.3 ± 0.7*** | 2.7 ± 0.3*** | 47 | ||||||
| hCav1.2 | 28.0 ± 1.7**,+++ | 14.3 ± 1.3*,++ | 3.1 ± 0.5* | 27 | ||||||
All values are presented as the mean ± SEM for the indicated number of experiments (n). V0.5, Half-maximal activation voltage; k, slope factor; act thresh, activation threshold; V0.5,inact, half-maximal inactivation voltage; kinact, inactivation slope factor. Parameters of voltage dependence of activation or inactivation were obtained as described in Methods and Materials. The r values represent the fraction of ICa remaining after 100, 250, or 5000 ms during a 5 s pulse to Vmax. Statistical significance was determined using one-way ANOVA (V0.5, k, act thresh, V0.5,inact, plateau, r100: p < 0.0001) with Bonferroni's post hoc test or Kruskal–Wallis (kinact; r250: p < 0.0001; r5000: p = 0.0009) with Dunn's multiple-comparison test. Statistical significances of post hoc tests are indicated for comparison vs hCav1.3L (*,**,***) and vs hCav1.3S (+,++,+++): ***p < 0.001; **p < 0.01; *p < 0.05.