Comparison of physiological parameters between QC and SC fibers and their responses to pruritic stimuli (cowhage and histamine)
| CMH (n = 43) | ||
|---|---|---|
| QC (n = 22) | SC (n = 21) | |
| Conduction velocity | 0.81 ± 0.04 | 0.85 ± 0.02 |
| Mechanical threshold | 1.5 ± 0.1 | 2.2 ± 0.17** |
| Heat threshold (°C) | 40.9 ± 0.25 | 45.0 ± 0.28*** |
| Response to 3s, 49°C (APs) | 26.3 ± 1.6 | 22.5 ± 3.3 (n = 16) |
| Response to cold bar (APs) | 11.5 ± 1.4 | 7.1 ± 2.7 |
| Cowhage | ||
| Total response (APs/ 5 min) | 97.1 ± 13.7 (n = 19) | 49.0 ± 8.3** (n = 20) |
| Number of bursts | 9.4 ± 1.8 (n = 19) | 7.2 ± 1.2 (n = 20) |
| Average intraburst frequency (1/t2) (Hz) | 6.6 ± 2.5 (n = 19) | 1.3 ± 0.18* (n = 20) |
| Average interburst interval (t1) (s) | 9.3 ± 1.3 (n = 19) | 15.3 ± 1.8* (n = 20) |
| Histamine | ||
| Total response (APs/5 min) | 29.8 ± 3.3 (n = 13) | 39.3 ± 5.4 (n = 16) |
| Number of bursts | 5.9 ± 1.3 (n = 13) | 7.8 ± 1.2 (n = 16) |
| Average intraburst frequency (1/t2) (Hz) | 8.5 ± 3.5 (n = 13) | 1.5 ± 0.37 (n = 16) |
| Average interburst interval (t1) (s) | 15.6 ± 2.2 (n = 13) | 18.3 ± 2.0 (n = 16) |
QC fibers had significantly smaller mechanical and heat thresholds, and the responses to cowhage were significantly larger, with a significantly higher intraburst frequency and a significantly smaller interburst interval. Histamine responses did not differ between QC and SC fibers.
*p < 0.01, Mann–Whitney U test (QC vs SC); **p < 0.01, unpaired t test (QC vs SC); ***p < 0.001, unpaired t test (QC vs SC).