Desensitization and recovery of ligand-gated ion channels
| Channel | Desensitization (sec) | Recovery (sec) | Ratio |
|---|---|---|---|
| P2X3 (transient nociceptor) | 0.03 | 460 | 15,000 |
| P2X2/3 (persistent nociceptor) | 4 | 60 | 15 |
| AMPA | 0.004 | 0.03 | 8 |
| Kainate | 1 | 60 | 60 |
| NMDA | 0.05 | 1 | 20 |
| GABA | 0.02 | 0.09 | 4.5 |
| Glycine | 1 | 20 | 20 |
| Nicotinic ACh | 0.05 | 2 | 40 |
| 5-HT3 | 0.4 | 30 | 80 |
| H+ | 0.5 | 20 | 40 |
Comparison of recovery and desensitization rates of various ligand-gated ion channels illustrates the unique nature of P2X3 current. Desensitization and recovery time constants are given in the first two columns and their ratio is in the third. For P2X3 current, this ratio is hundreds-fold larger than those of other ligand-gated ion channels. P2X3 may be especially sensitive therefore to modulation of recovery rate. (Data from Konnerth et al., 1987; Bufler et al., 1993;Jones and Westbrook, 1996; Barann et al., 1997; Cook and McClesky, 1997a; Wilding and Huettner, 1997).