Table 2.
Excitability parameters (means ± S.D.) from tail muscle recordings of mice in vivo, before (control, n = 15 mice) and approximately 45 min after injection of PBS containing methanol (1%) and PnTX-A (5.44 nmol/kg of mouse, n = 8 mice).
| Test 1 | Excitability Parameter 2 | Control | PnTX-A | P |
|---|---|---|---|---|
| T1 | Peak response (mV) | 3.299 ± 1.140 | 1.847 ± 1.370 | 0.050 * |
| Latency (ms) | 3.359 ± 0.065 | 3.349 ± 0.106 | 0.893 | |
| Stimulus (mA) for 50% max response | 0.481 ± 1.060 | 0.479 ± 1.130 | 0.927 | |
| Stimulus-response slope | 3.004 ± 1.180 | 2.650 ± 1.310 | 0.743 | |
| T2 | Resting slope | 0.638 ± 0.077 | 0.916 ± 0.257 | 0.182 |
| Minimum slope | 0.230 ± 0.013 | 0.218 ± 0.022 | 0.703 | |
| Hyperpolarizing slope | 0.536 ± 0.071 | 0.490 ± 0.074 | 0.757 | |
| T3 | Strength-duration time constant (ms) | 0.377 ± 0.035 | 0.316 ± 0.036 | 0.274 |
| Rheobase (mA) | 0.333 ± 1.070 | 0.327 ± 1.130 | 0.861 | |
| T4 | TEd (10–20 ms) | 47.680 ± 2.570 | 45.250 ± 4.930 | 0.700 |
| TEd (peak) | 48.640 ± 2.320 | 45.240 ± 4.110 | 0.555 | |
| TEd (40–60 ms) | 39.440 ± 3.000 | 38.080 ± 1.980 | 0.826 | |
| TEd (90–100 ms) | 36.000 ± 3.010 | 35.230 ± 1.810 | 0.878 | |
| TEd (accommodation) | 12.590 ± 1.230 | 10.170 ± 2.890 | 0.441 | |
| TEd (undershoot) | −11.820 ± 1.120 | −5.188 ± 0.512 | 0.019 * | |
| TEh (10–20 ms) | −97.600 ± 4.780 | −86.230 ± 2.660 | 0.318 | |
| TEh (20–40 ms) | −132.000 ± 8.430 | −123.900 ± 7.160 | 0.686 | |
| TEh (90–100 ms) | −159.20 ± 12.60 | −150.300 ± 4.910 | 0.753 | |
| TEh (overshoot) | 13.350 ± 1.460 | 7.238 ± 1.450 | 0.079 | |
| T5 | Relative refractory period (ms) | 2.349 ± 1.090 | 2.532 ± 1.100 | 0.632 |
| Superexcitability (%) | −7.596 ± 1.490 | −9.049 ± 1.970 | 0.600 | |
| Subexcitability (%) | 3.844 ± 0.708 | 3.316 ± 1.160 | 0.697 |
1 T1 = Stimulus-response relationship, T2 = Current-threshold relationship (informed on accommodation capacity to depolarizing and hyperpolarizing currents), T3 = Strength-duration relationship (informed on nodal membrane potential), T4 = Threshold electrotonus and T5 = Recovery cycle. 2 TEd = Threshold electrotonus from depolarizing currents and TEh = Threshold electrotonus from hyperpolarizing currents. *: Significant difference compared to control.