Table 2.
Action potentials and voltage-gated currents in cold-sensitive and cold-insensitive DRG neurones
| Cold-sensitive | n | Cold-insensitive | n | P* | |
|---|---|---|---|---|---|
| Diameter (μm) | 18.8 ± 1.6 | 32 | 20.7 ± 2.2 | 60 | <0.001 |
| Action potential parameter: | |||||
| Resting potential (mV) | −53.0 ± 7.0 | 21 | −51.6 ± 5.0 | 38 | n.s |
| Amplitude (mV) | 93.2 ± 13.6 | 21 | 89.3 ± 11.6 | 38 | n.s. |
| Duration at takeoff voltage (ms) | 3.6 ± 1.5 | 21 | 89.3 ± 11.6 | 38 | n.s. |
| After-hyperpolarisation (AHP) (mV) | 4.4 ± 2.9** | 16 | 12. ± 4.7 | 38 | <0.001 |
| AHP-hyperpolarisation (AHP) (mV) | 100 ± 96** | 13 | 112 ± 68 | 38 | n.s. |
| Number showing inflection | 8/21(38%) | 27/38(71%) | <0.001 (X2test) | ||
| Voltage-gated currents: | |||||
| Ih amplitude (pA) | 106 ± 79 | 33 | 71.4 ± 47 | 63 | 0.008 |
| Decay time constant of transient inward current (ms) | 0.9 ± 0.2 | 32 | 2.3 ± 0.9 | 63 | <0.0001 |
| Number expressing A-type K+ current | 14/33(42%) | 50/64(78%) | <0.001 (X2 test) | ||
| Cold-sensitive neurones only: | Capsaicin-sensitive | Capsaicin-insensitive | |||
|---|---|---|---|---|---|
| Ih amplitude (pA) | 90.0 ± 55 | 14 | 191 ± 89 | 7 | 0.004 |
| Action potential duration (ms) | 31. ± 0.7 | 14 | 4.5 ± 2.2 | 7 | 0.04 |
*
Student's unmpaired t test unless stated
**
AHP absent in 5 neurones and too small to measure duration in a further 3 neurones.