The Collaborative International Dictionary of English v.0.48:

bradykinin \bra`dy*ki"nin\ n.
   a hypotensive tissue hormone (C50H73N15O11) which acts on
   smooth muscle, dilates peripheral vessels and increases
   capillary permeability. It is formed locally in injured
   tissue and is believed to play a role in the inflammatory
   process. It is a nonapeptide with the sequence:
   Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg. --MI11

   Syn: kallidin I; callidin I; kallidin-9.
        [PJC]