Recovery from rapid inactivation
| V (mV) | τ1(msec) | A1 | τ2(msec) | A2 | |
|---|---|---|---|---|---|
| NaII (α) | −90 | 3.12 ± 0.02 | |||
| (n = 3) | |||||
| −120 | 1.25 ± 0.03 | ||||
| (n = 3) | |||||
| NaIIA (α) | −90 | 4.14 ± 1.95 | 0.46 ± 0.18 | 113.5 ± 81.6 | 0.54 ± 0.02 |
| (n = 9) | (n = 9) | ||||
| −120 | 7.79 ± 2.39 | 0.40 ± 0.03 | 67.5 ± 21.9 | 0.60 ± 0.02 | |
| (n = 6) | (n = 6) | ||||
| NaIIA (α + β1) | −90 | 4.98 ± 0.50 | |||
| (n = 4) | |||||
| −120 | 1.30 ± 0.06 | ||||
| (n = 3) |
Rates of recovery from the rapid inactivation states are derived by fitting an exponential function to the maxima of inward currents during the recovery phase in double-pulse experiments (as demonstrated in Fig. 1A). In the case of NaIIA (α subunit only) channel, fitting necessitates at least two exponential terms. One exponential term is sufficient in the case of NaII and in the case of NaIIA isoform that is coexpressed with a β1 subunit. Time constants (τ), relative amplitudes (A), SDs, and number of experiments are given for −90 and −120 mV.