Electrophysiological properties of sensory neurons observed 5–10 days after axotomy
| Property | Control Cells | Axotomized Cells | n (Animals) | P |
|---|---|---|---|---|
| RMP, mV | −45.9 ± 0.9 | −43.0 ± 0.6 | 16 | 0.013 |
| R in, MΩ | 20.9 ± 2.2 | 38.5 ± 5.0 | 16 | 0.002 |
| Sag (<0.95) | 93% of 30 cells | 63% of 30 cells | 9 | 0.010 |
| τ, ms | 17.8 ± 2.6 | 38.7 ± 6.7 | 9 | 0.028 |
| C in, pF | 461 ± 28 | 651 ± 63 | 7 | 0.029 |
| Threshold, 20 ms, nA | 0.79 ± 0.05 | 0.67 ± 0.06 | 9 | 0.20 |
| Excitability (spikes) | ||||
| 2.5 × threshold | 5.3 ± 0.5 | 16.0 ± 1.2 | 9 | 0.00006 |
| 2 nA | 4.5 ± 0.5 | 17.8 ± 1.5 | 9 | 0.00001 |
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Except for the sag measurements, all values are means ± SE, with each animal contributing a single average from the axotomized cells in one pleural sensory cluster and another from the control cells in the contralateral cluster (2–8 cells sampled in each cluster). The values of P were determined with two-tailed pairedt-tests or, in the case of sag, with Fisher's exact test. Sag was defined as ΔV m (end hyperpolarization)/ ΔV m (peak hyperpolarization) < 0.95 (see Fig. 1). Sag and τ were measured during 2-s, 0.6-nA hyperpolarizing pulses. R inwas determined with 1-s, 0.5-nA hyperpolarizing pulses.C in was estimated by integrating capacity transients during 10-ms, 10-mV steps under voltage clamp. Excitability refers to the number of action potentials (spikes) evoked by a 1-s depolarizing pulse with a current of either 2 nA or 2.5 × the threshold current required to evoke a single spike with a 20-ms pulse. All measurements came from the same axotomized or control cells in 9 animals, except for C in measurements, which came from 7 additional animals that were used for voltage clamp studies. RMP and R in measurements came from both groups of animals.