Table 1.
FHF protein and peptide modulation of Nav1.6 currents
| No FHF | FHF1A | FHF1B | FHF2A | FHF2B | FHF4A | FHF4B | F2A(2–21) 1 mm peptide | ||
|---|---|---|---|---|---|---|---|---|---|
| Long term inactivation | % Available 40 ms after depolarization | ||||||||
| Cycle 1 | 94.3 ± 2.4 | 76.4 ± 3.8 | 95.2 ± 2.8 | 70.2 ± 5.2 | 95.1 ± 2.2 | 58.9 ± 6.3 | 93.6 ± 5.3 | 62.0 ± 8.8 | |
| Cycle 2 | 92.4 ± 4.8 | 69.7 ± 1.8 | 93.0 ± 4.8 | 56.7 ± 6.7 | 94.0 ± 3.8 | 47.1 ± 7.7 | 94.6 ± 7.3 | 48.1 ± 9.8 | |
| Cycle 3 | 91.4 ± 4.9 | 64.3 ± 1.8 | 92.6 ± 5.0 | 48.8 ± 7.3 | 93.6 ± 2.8 | 42.1 ± 7.2 | 94.6 ± 6.2 | 40.5 ± 9.4 | |
| No. of cells | n= 11 | n= 5 | n= 6 | n= 9 | n= 10 | n= 5 | n= 11 | n= 11 | |
| t test P value | 3 × 10−10 | 8 × 10−10 | 4 × 10−8 | 4 × 10−11 | |||||
| Tau recovery (ms) | |||||||||
| at −90 mV | 131 ± 41 | 371 ± 107 | 206 ± 67 | 323 ± 14 | |||||
| No. of cells | n= 4 | n= 9 | n= 5 | n= 4 | |||||
| at −110 mV | N.A. | 153 ± 33 | N.A. | N.A. | |||||
| No. of cells | n=5 | ||||||||
| V1/2 (mV) | −46.6 ± 2.7 | −46.7 ± 5.3 | −47.4 ± 2.1 | −42.7 ± 5.0 | |||||
| k factor (mV) | −4.0 ± 0.2 | −4.3 ± 0.4 | −3.3 ± 0.4 | −6.8 ± 1.1 | |||||
| No. of cells | n= 4 | n= 6 | n= 4 | n= 6 | |||||
| Steady state inactivation | V1/2 (mV) | −79.1 ± 3.7 | −66.4 ± 2.8 | −78.0 ± 2.6 | −66.3 ± 4.3 | −71.5 ± 2.2 | −63.3 ± 3.3 | −62.3 ± 4.3 | −77.1 ± 3.2 |
| k factor (mV) | −5.5 ± 0.5 | −5.0 ± 0.2 | −5.6 ± 0.3 | −5.6 ± 0.3 | −5.5 ± 0.5 | −6.1 ± 0.8 | −6.8 ± 1.4 | −5.3 ± 0.5 | |
| No. of cells | n= 8 | n= 5 | n= 5 | n= 8 | n= 8 | n= 5 | n= 8 | n= 7 | |
| t test P value | 3 × 10−5 | 2 × 10−5 | 3 × 10−4 | 2 × 10−5 | 1 × 10−6 | ||||
| Activation | V1/2 (mV) | −35.0 ± 3.3 | −40.0 ± 3.9 | −38.3 ± 1.3 | −39.1 ± 7.0 | −36.6 ± 3.1 | −37.6 ± 4.6 | −36.1 ± 3.7 | −34.4 ± 6.3 |
| No. of cells | n= 7 | n= 5 | n= 4 | n= 7 | n= 6 | n= 5 | n=6 | n=7 |
TTX-resistant sodium currents in N2A-Nav1.6TTXr cells were analysed after transient transfection with FHF expression plasmids or perfusion with FHF2A-derived N-terminal peptide F2A(2–21). Accumulating long-term inactivation was assayed using four 16 ms 0 mV depolarizations separated by 40 ms −90 mV recovery intervals. Recovery was assayed by varying the duration of a −90 mV recovery interval following three prior depolarization pulses. Voltage dependences for activation, steady state inactivation, and long-term inactivation were analysed using protocols described in Methods. Values shown as means ± standard deviation. Statistical significance by t tests were determined by comparing values for a given test group to those obtained in absence of FHF plasmid or peptide; highly significant values are highlighted in italic. V1/2, voltage of half-maximal effect; k, slope factor; N.A, not analysed. Also see Suppl. Fig. 2 showing lack of TTX-resistant current in parental N2A cells.