Table 2. Comparison of mean biophysical and permeability parameters of in vitro expressed Cav3 channels (±SE; n values in parentheses).
| Parameter | TCav3 | LCav3 (+8b-25c) | P-value | Ref. | Cav3.1 | P-value | Ref. | Cav3.2 | P-value | Ref. | Cav3.3 | P-value | Ref. |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Activation | |||||||||||||
| Peak of IV (mV) | −45 | −40 | 1 | −35 | 2 | −35 | 2 | −25 | 2 | ||||
| V1/2 | −59.32 ± 0.9 (8) | −53.48 ± 0.34 (13) | *** | 1 | −49.3 ± 0.7 (26) | *** | 2 | −48.4 ± 1.2 (10) | *** | 2 | −41.5 ± 1.1 (17) | *** | 2 |
| Slope (k, mV) | 4.50 ± 0.25 (8) | 5.46 ± 0.14 (13) | ** | 1 | 4.6 ± 0.1 (26) | NS | 2 | 5.2 ± 0.4 (10) | NS | 2 | 6.2 ± 0.2 (17) | *** | 2 |
| Inactivation | |||||||||||||
| V1/2 | −74.15 ± 0.90 (10) | −70.89 ± 0.49 (16) | ** | 1 | −74.2 ± 1.1 (8) | NS | 2 | −75.6 ± 0.7 (19) | NS | 2 | −69.8 ± 0.9 (17) | ** | 2 |
| Slope (k, mV) | 2.69 ± 0.11 (8) | 2.93 ± 0.08 (16) | NS | 1 | 5.5 ± 0.3 (8) | *** | 2 | 6.2 ± 0.2 (19) | *** | 2 | 6.1 ± 0.1 (17) | *** | 2 |
| Activation kinetics | |||||||||||||
| τ (−50 mV) | 14.36 ± 0.31 (8) | 3.26 ± 0.13 (16) | *** | 1 | 8.2 ± 0.9 (8) | *** | 3 | 9.9 ± 0.4 (10) | *** | 3 | 43 ± 3 (9) | *** | 3 |
| τ (−10 mV) | 3.48 ± 0.13 (8) | 0.74 ± 0.03 (16) | *** | 1 | 1.1 ± 0.1 (8) | *** | 3 | 1.8 ± 0.1 (10) | *** | 3 | 5.9 ± 0.5 (9) | *** | 3 |
| Fold change | 4.1 | 4.4 | 7.5 | 5.5 | 7.3 | ||||||||
| Inactivation kinetics | |||||||||||||
| τ (−50 mV) | 66.33 ± 3.39 (6) | 27.51 ± 1.34 (16) | *** | 1 | 62 ± 23 (8) | NS | 3 | 28 ± 3 (10) | *** | 3 | 126 ± 22 (9) | * | 3 |
| τ (−10 mV) | 51.36 ± 1.53 (6) | 15.67 ± 0.56 (16) | *** | 1 | 16 ± 1 (8) | *** | 3 | 15 ± 1 (10) | *** | 3 | 80 ± 5 (9) | *** | 3 |
| Fold change | 1.3 | 1.8 | 3.9 | 1.9 | 1.6 | ||||||||
| Deactivation | |||||||||||||
| −100 mV | 1.46 ± 0.06 (12) | 1.37 ± 0.05 (19) | NS | 1 | 2.6 ± 0.2 (9) | *** | 2 | 3.6 ± 0.4 (14) | *** | 2 | 1.12 ± 0.1 (31) | * | 2 |
| −70 mV | 9.15 ± 0.66 (12) | 2.28 ± 0.18 (19) | *** | 1 | 6.2 ± 0.4 (9) | ** | 2 | 8.5 ± 1.1 (14) | NS | 2 | 2.1 ± 0.1 (30) | *** | 2 |
| Recovery | |||||||||||||
| τ recovery (ms) | 1275.05 ± 54.43 (6) | 908.04 ± 27.05 (14) | *** | 1 | 137 ± 5 (12) | *** | 2 | 448 ± 36 (7) | *** | 2 | 260 ± 30 (18) | *** | 2 |
| Nickel | |||||||||||||
| (IC50 µM) | 335.0 ± 6.5 (9) | 300.0 ± 29.2 (4) | NS | 4 | 304.8 ± 6.2 (5–6) | * | 5 | 4.9 ± 2.0 (5–6) | *** | 5 | 216 ± 9 (5-6) | *** | 5 |
| Mixed Ca2+/Na+ currents | |||||||||||||
| % increase in Imax (Ca2+) | 42.09 ± 3.19 (8) | 12a: 1439.75 ± 82.50 (6) | *** | 6 | 26.64 ± 9.24 (4) | * | 31.96 ± 4.58 (11) | NS | 45.45 ± 7.59 (6) | NS | |||
| 12b: 153.02 ± 9.61 (7) | *** | 6 | |||||||||||
| % increase in Imax (Ba2+) | 51.19 ± 2.64 (4) | 12a: 901.29 ± 120.33 (5) | *** | 6 | 27.01 ± 3.17 (9) | *** | 6 | 36.88 ± 3.50 (7) | * | 6 | 49.91 ± 6.23 (4) | NS | 6 |
| 12b: 121.07 ± 4.26 (3) | *** | 6 | |||||||||||
| Ca2+ vs. X+ permeability | |||||||||||||
| pCa/pLi | 19.87 ± 1.30 (8) | 12a: 22.74 ± 0.41 (8) | * | 6 | 46.67 ± 2.32 (7) | *** | 6 | ||||||
| 12b: 27.40 ± 1.13 (7) | *** | 6 | |||||||||||
| pCa/pNa | 35.61 ± 1.52 (8) | 12a: 33.06 ± 1.50 (6) | NS | 6 | 89.56 ± 8.21 (6) | *** | 6 | 80.58 ± 3.69 (4) | *** | 56.19 ± 2.99 (7) | *** | ||
| 12b: 41.49 ± 1.98 (8) | * | 6 | |||||||||||
| pCa/pK | 63.99 ± 4.19 (9) | 12a: 50.25 ± 1.56 (12) | ** | 6 | 140.16 ± 12.02 (5) | *** | 6 | ||||||
| 12b: 78.93 ± 4.17 (11) | * | 6 | |||||||||||
| pCa/pCs | 114.83 ± 10.64 (7) | 12a: 111.30 ± 8.57 (10) | NS | 6 | 154.65 ± 7.99 (5) | * | 6 | ||||||
| 12b: 113.76 ± 7.19 (11) | NS | 6 | |||||||||||
P-values for statistical comparisons for all channels with respect to TCav3 were generated using one-way ANOVA. *, P < 0.05; **, P < 0.005; ***, P < 0.0005; NS, not significantly different. Bold indicates the value most similar to TCav3, and bold italics indicates the value most different from TCav3. References: 1, Senatore and Spafford (2012); 2, Chemin et al. (2002); 3, Gomora et al. (2002); 4, Senatore and Spafford (2010); 5, Kang et al. (2006); 6, Senatore et al. (2014).