Bradykinin
Bradykinin is a short vasoactive peptide that widens blood vessels, increases vascular permeability, and contributes to pain and inflammation.
Kinin–kallikrein system: A proteolytic system that generates kinins, including bradykinin, from kininogen precursors. This is the pathway that produces bradykinin and regulates its release.
Hereditary angioedema: An inherited disorder causing recurrent, potentially dangerous swelling from excess bradykinin signaling. Excess bradykinin is a principal mediator of swelling in this disorder.
Kininogen: A plasma protein precursor from which proteases release kinins such as bradykinin. Bradykinin is excised from high-molecular-weight kininogen by kallikrein.
Histamine: A biogenic amine that acts as a neurotransmitter and mediator of allergic and inflammatory responses. Like bradykinin, histamine can increase vascular permeability, but it uses different receptors and pathways.
Bradykinin B1 receptor: An inducible G protein-coupled receptor activated mainly by des-Arg kinins. Inflammation can induce this receptor, extending bradykinin-family signaling.
Icatibant: A selective bradykinin B2-receptor antagonist used to treat acute hereditary angioedema attacks. It blocks bradykinin signaling at the receptor driving many acute attacks.
Plasma kallikrein: A serine protease that releases bradykinin from high-molecular-weight kininogen. It is the key enzyme generating bradykinin in the plasma contact system.
Substance P: A neuropeptide involved in pain transmission, neurogenic inflammation, and other signaling functions. Both peptides can contribute to pain and inflammation, but arise from distinct signaling systems.
Bradykinin B2 receptor: A constitutively expressed G protein-coupled receptor activated by bradykinin and kallidin. This receptor mediates many rapid vascular and sensory effects of bradykinin.
C1-inhibitor: A serine protease inhibitor that regulates complement, contact, and kinin–kallikrein pathways. Deficiency or dysfunction can permit excessive bradykinin production.