Fig. 6

Effect of PAR₂-AP on nociceptive responses to intraplantar injection of acetic acid in rats. The a bar graph shows that the nociceptive responses are evoked by intraplantar injection of acetic acid (30 μl, pH 6.0) in the presence of the TRPV1 inhibitor capsazepine (100 μM). The pretreatment of PAR₂-AP increased the flinching behavior induced by acetic acid in a dose-dependent manner (1–10 μg). The effect of PAR₂-AP (10 μg) was blocked by co-treatment of FSLLRY-NH2 (20 μg), a selective PAR₂ antagonist. *P < 0.05, **P < 0.01, Bonferroni’s post hoc test, compared with control; ##P < 0.01, Bonferroni’s post hoc test, compared with PAR₂-AP (10 μg) column. The b bar graph shows that the acidosis-evoked nociception and increased pain response induced by PAR₂-AP (10 μg) were blocked by pretreatment with APETx2 (20 μl, 20 μM), an ASIC3 inhibitor. **P < 0.01, Bonferroni’s post hoc test, compared with control; ##P < 0.01, Bonferroni’s post hoc test, compared with PAR₂-AP column. Each bar represents the number of flinches that the animals spent licking/lifting the injected paw during first 5-min observation period (mean ± SEM of 10 rats in each group)