- The nonapeptide Arg–Pro–Pro–Gly–Phe–Ser–Pro–Phe–Arg, produced from the decapeptide kallidin (bradykininogen) that is produced from α2-globulin by kallikrein, normally present in blood in an inactive form and similar to trypsin in action; b. is one of a number of the plasma kinins, is a potent vasodilator, and is one of the physiologic mediators of anaphylaxis released from cytotropic antibody-coated mast cells following reaction with antigen (allergen) specific for the antibody. SYN: kallidin 9, kallidin I, kinin 9. [brady- + G. kineo, to move]
* * *bra·dy·ki·nin -'kī-nən n a kinin that is formed locally in injured tissue, acts in vasodilation of small arterioles, is considered to play a part in inflammatory processes, and is composed of a chain of nine amino acid residues see KALLIDIN
* * *n.a naturally occurring polypeptide consisting of nine amino acids. Bradykinin is a very powerful vasodilator and causes contraction of smooth muscle; it is formed in the blood under certain conditions and is thought to play an important role as a mediator of inflammation. See kinin.
* * *brady·ki·nin (brad″e-kiґnin) [brady- + Gr. kinein to move] a nonapeptide (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg) produced by activation of the kinin system in a variety of inflammatory conditions. It is a potent vasodilator and also increases vascular permeability, stimulates pain receptors, and causes contraction of a variety of extravascular smooth muscles. The name refers to the slowly developing contraction produced in isolated guinea pig ileum. It is produced by the action of plasma kallikrein, trypsin, or plasmin on high-molecular-weight kininogen, a plasma α2-globulin, and is destroyed by several kininases in the lungs and other tissues.
Medical dictionary. 2011.