Intradermal administration of ICI 118,551 (1 µg/paw) 15 min prior to endothelin, abolished stimulus-induced enhancement of endothelin hyperalgesia (A, P < 0.001, two way repeated measures ANOVA followed by Bonferroni post test, n = 8/group) without affecting the endothelin hyperalgesia. Intradermal administration of ICI 118,551 (1 µg/paw) 15 min prior to epinephrine abolished both epinephrine hyperalgesia and stimulus-induced enhancement of hyperalgesia (B, for both P < 0.001, two way repeated measures ANOVA followed by Bonferroni post test, comparing results within and between groups at different time points, n = 12/group).