Pro-inflammatory effects of bradykinin, sigma-cyclo[Lys1,Gly6]bradykinin and sigma-cyclo-kallidin in the rat.

A comparison of the effects of bradykinin (BK), sigma-cyclo-BK and sigma-cyclo-kallidin (sigma-cyclo-KD) to induce oedema, hyperalgesia and blood flow in the rat paw was made. BK produced dose-dependent increases in oedema and blood flow and a reduction in the nociceptive pressure threshold. Sigma-Cyclo-BK and sigma-cyclo-KD were more potent than BK at inducing oedema and increasing blood flow but had no effect on nociceptive pressure threshold at the doses used. The relative lack of hyperalgesic activity of sigma-cyclo-BK and sigma-cyclo-KD compared with BK raises the possibility of differences between kinin receptors mediating permeability and blood flow changes and those involved in nociception in this model.