Bradykinin Receptor
A receptor for bradykinin, a peptide that causes vasodilation, increases vascular permeability, and mediates pain and inflammation. The B2 receptor subtype is the target of icatibant, a peptide antagonist used to treat acute attacks of hereditary angioedema by blocking bradykinin-induced swelling.
Technical Context
Bradykinin is a 9 amino acid peptide cleaved from high-molecular-weight kininogen by the enzyme kallikrein during activation of the contact (kinin-kallikrein) system. It acts on two receptors: B1 (induced during inflammation) and B2 (constitutively expressed). B2 receptor activation causes vasodilation, increased vascular permeability, pain, and smooth muscle contraction. In hereditary angioedema, C1-esterase inhibitor deficiency leads to uncontrolled bradykinin production and severe swelling. Icatibant is a synthetic decapeptide (10 amino acids) that contains five non-natural amino acids, making it a potent competitive B2 receptor antagonist resistant to proteolytic degradation, with a half-life of approximately 1-2 hours.