Effects of substance P and capsaicin on synovitis in the presence and absence of neurokinin antagonists
Increases in knee diameter and macrophage infiltration 24 h after intra-articular injection of 10 nmol of substance P (+) or 0.5% capsaicin (+), compared with normal saline (–), were not inhibited by coadministration of NK1 or NK2 receptor antagonists. Geometric means (95% confidence interval) of six rats.
Substance P | Capsaicin | |||||
|---|---|---|---|---|---|---|
| Diameter (mm) | - | 9.0 (95% CI, 8.9-9.2)* | - | 9.1 (95% CI, 9-9.2)* | ||
| + | 9.4 (95% CI, 9.3-9.6) | + | 9.6 (95% CI, 9.5-9.8) | |||
| + SR140333 | 9.2 (95% CI, 8.6-9.9) | + SR140333 | 9.4 (95% CI, 8.9-10.1) | |||
| + SR140603 | 10.5 (95% CI, 10.1-11.0) | + SR140603 | 9.1 (95% CI, 8.5-10.4) | |||
| + SR140190 | 9.4 (95% CI, 8.8-10.1) | / | / | |||
| Macrophage area (%) | - | 3.5 (95% CI, 2.9-4.3)* | - | 2.8 (95% CI, 2.3-3.5)* | ||
| + | 9.6 (95% CI, 7.8-11.8) | + | 10.3 (95% CI, 6.6-16.1) | |||
| + SR140333 | 7.3 (95% CI, 5.7-9.3) | + SR140333 | 8.0 (95% CI, 5.6-11.3) | |||
| + SR140603 | 8.7 (95% CI, 4.7-12.8) | + SR140603 | 8.6 (95% CI, 6.7-11.1) | |||
|
| + SR140190 | 10.3 (95% CI, 6.9-15.3) | / | / | ||
↵* p < 0.05 compared with knees injected with substance P or capsaicin alone.