Table 2.
Voltage-dependent inactivation properties of VDCC constructs for a 1.5 s depolarization to the peak of the current density-voltage relationship
| Construct | n | τfast (MS) | Fast component (%) | τslow (MS) | Slow component (%) | Non-inactivating component (%) |
|---|---|---|---|---|---|---|
| α1B | 4 | 77 ± 10 | 55 ± 8 | 413 ± 34 | 41 ± 7 | 4 ± 1 |
| α1B/α2-δ | 6 | 93 ± 6 | 52 ± 5 | 474 ± 31 | 43 ± 5 | 5 ± 2 |
| α1B/α2 δ/β2a* | — | — | — | — | — | — |
| α1B/α2-δ/β2a(C3,4S) | 4 | 187 ± 38 | 37 ± 8 | 753 ± 55 | 44 ± 4 | 18 ± 6 |
| α1BΔ1–55/α2-δ/β2a | 4 | 167 ± 42 | 11 ± 3 | 4760 ± 857 | 44 ± 4 | 45 ± 7 |
| α1BΔ2–50/α2-δ/β2a | 4 | 168 ± 61 | 19 ± 3 | 1888 ± 202 | 36 ± 4 | 45 ± 4 |
| α1B/α2-δ/β1b | 8 | 155 ± 35 | 48 ± 6 | 704 ± 120 | 40 ± 5 | 12 ± 1 |
| α1BΔ1–55/α2-δ/β1b | 7 | 137 ± 12 | 61 ± 3 | 793 ± 176 | 34 ± 4 | 6 ± 1 |
| α1B/α2-δ/β3 | 8 | 169 ± 23 | 52 ± 7 | 758 ± 79 | 38 ± 6 | 10 ± 2 |
| α1BΔ1–55/α2-δ/β3 | 7 | 130 ± 23 | 42 ± 7 | 506 ± 49 | 47 ± 6 | 10 ± 5 |
| α1B/α2-δ/β4 | 6 | 264 ± 87 | 26 ± 7 | 1003 ± 111 | 51 ± 6 | 23 ± 4 |
| α1BΔ1–55/α2-δ/β4 | 10 | 266 ± 26 | 32 ± 5 | 951 ± 101 | 49 ± 5 | 19 ± 3 |
| α1B(R52A)/α2-δ/β2a | 4 | 259 ± 83 | 9 ± 3 | 1755 ± 209 | 40 ± 5 | 51 ± 8 |
| α1B(Q47A)/α2-δ/β2a | 3 | 63 ± 27 | 9 ± 2 | 1141 ± 51 | 41 ± 3 | 50 ± 6 |
| α1B(R52,54A)/α2-δ/β2a | 3 | 280 ± 178 | 8 ± 4 | 1401 ± 70 | 41 ± 4 | 51 ± 1 |
| α1B(R52,54A) | 5 | 78 ± 9 | 58 ± 6 | 418 ± 69 | 34 ± 4 | 8 ± 3 |
*
It was not possible to fit parameters to α1B/α2-δ/β2a currents, as described in the text. For all other combinations, current decay was well fitted with a double exponential function (see Methods). In a very small number of cases, current decayed with a single slow exponential function and the fast component was assumed to be zero.