Bradykinin B1 Receptor (B1R)

Bradykinin B1 receptor (B1R) is rapidly induced after tissue trauma and helps maintain inflammatory responses^[1]. Mechanistically, B1R up-regulation in human lung fibroblasts responds to desArg10-kallidin and interleukin-1β through distinct but synergistic tyrosine kinase, p38 MAPK, and NF-κB-sensitive pathways^[1]. In inflammatory pain models, kinins activate both B1 and B2 receptors, while des-Arg-BK and des-Arg-KD activate B1R^[2]. Compared with B2R, B1R preferentially supports chronic inflammatory pain responses, whereas B2R supports acute-phase responses^[2]. Ligand studies further distinguish B1R because high-affinity human B1R binding requires an N-terminal L-lysine interaction with the fourth extracellular domain^[3]. For experimental applications, potent B1R antagonists inhibit des-Arg-kallidin binding, phosphatidylinositol turnover, and calcium mobilization, while showing inactivity at B2R^[4].