Table 1.
Summary of channel properties and amantadine sensitivity
| Variable | Relative specific activity (%) | Reversal voltage (mV)* | Percentage of inhibition (%)† | IC50 (μM) amantadine‡ |
|---|---|---|---|---|
| A/M2 WT | NA | 75.5 ± 4.8 | 97.3 ± 1.0 | 16.0 ± 1.2 |
| A/M2 S31N | NA | 76.7 ± 1.5 | 31.6 ± 1.7 | 199.9 ± 13.5 |
| A/M2 (21–97) | NA | 73.2 ± 2.4 | 92.3 ± 0.7 | 45.7 ± 2.1 |
| A/M2 (21–97) S31N | NA | 74.7 ± 3.4 | 9.7 ± 3.2 | 1,554.9 ± 111.7 |
| BM2 (24–36aaA/M2) | 25.2 ± 1.8 | 75.3 ± 6.0 | 44.7 ± 2.6 | NA |
| BM2 (24–36aaA/M2) S31N | 44.7 ± 3.0 | 75.0 ± 1.5 | 5.1 ± 3.1 | NA |
| BM2 (19–36aaA/M2) | 106.0 ± 8.1 | 75.3 ± 4.7 | 83.6 ± 1.6 | 58.1 ± 3.7 |
| BM2 (19–36aaA/M2) S31N | 111.6 ± 9.1 | 76.5 ± 2.5 | 34.0 ± 1.2 | 611.1 ± 14.1 |
| BM2 d2–5 (19–36aaA/M2) | 116.4 ± 18.6 | 85.7 ± 2.2 | 73.9 ± 1.4 | 59.6 ± 4.0 |
| BM2 d2–5 (19–36aaA/M2) S31N | 109.8 ± 10.7 | 91.2 ± 1.7 | 14.0 ± 3.0 | 1,459.5 ± 86.1 |
| BM2 WT | 100.0 | 78.4 ± 0.6 | 3.7 ± 2.3 | NA |
| BM2 (37–45aaA/M2) | 73.1 ± 2.4 | 73.0 ± 2.3 | 2.6 ± 1.1 | NA |
Data are shown as mean ± SE. NA, not available
*For the measurement of reversal voltage, membrane voltage ramp measurements were made at pH 5.5 at the time when the amplitude of the steady inward current was maximal (approximately 10 s after lowering the bath solution to pH 5.5). Current–voltage relationship was plotted after subtraction of pH 8.5 background current from pH 5.5 current.
†Measurements were done after 5-min incubation with 100 μM amantadine at pH 5.5.
‡Measurements were done after 2-min incubation with amantadine at pH 5.5.