Antinociceptive activity of the bradykinin B₁ and B₂ receptor antagonists, des-Arg⁹, [Leu⁸]-BK and HOE 140, in two models of persistent hyperalgesia in the rat

There has been recent evidence linking bradykinin (BK) receptors with inflammation. This study has investigated the involvement of BK receptors in two models of persistent inflammatory hyperalgesia in rats. In a Freund's adjuvant-induced hyperalgesia model and an ultraviolet (UV)-induced hyperalgesia model in rats the specific B₂ antagonist, D-Arg[Hyp³, Thi⁵, D-Tic⁷, Oic⁸]-BK (HOE 140), was either ineffective or weakly active in reversing hyperalgesia. The specific B₁ antagonist, des-Arg⁹, [Leu⁸]-BK, was effective in reversing or preventing the development of hyperalgesia in both Freund's adjuvant-induced hyperalgesia and UV-induced hyperalgesia. The B₁ agonist, des-Arg⁹-BK, produced a small exacerbation of hyperalgesia in both models. Data suggest that in persistent inflammatory conditions in the rat bradykinin B₁ receptors are involved in the accompanying hyperalgesia.