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Bradykinin is a "nonapeptide messenger that is enzymatically produced from kallidin in the blood where it is a potent but short-lived agent of arteriolar dilation and increased capillary permeability. Bradykinin is also released from mast cells during asthma attacks, from gut walls as a gastrointestinal vasodilator, from damaged tissues as a pain signal, and may be a neurotransmitter.[1]

There are two bradykinin receptors.

Bradykinin is degraded by kininase I and kininase II.[2] Kininase II, formally called peptidyl-dipeptidase A, is the same enzyme as angiotensin converting enzyme.

Clinical roles

Cough when taking angiotensin-converting enzyme inhibitors may be due to deficient degradation of bradykinin by kininase II (angiotensin-converting enzyme).[3] According to a clinical prediction rule, cough due to angiotensin-converting enzyme inhibitors is more likely among patients who are "older age, female gender, non-African American (with East Asian having highest risk), no history of previous angiotensin-converting enzyme inhibitor use, and history of cough due to another angiotensin-converting enzyme inhibitor".[4]

Hereditary angioedema may be due to unregulated kallikrein activation of bradykinin due to insufficient complement C1 inhibitor protein (C1 esterase inhibitor)..[5]


  1. Anonymous (2023), Bradykinin (English). Medical Subject Headings. U.S. National Library of Medicine.
  2. Ganong, William F. (2005). Review of medical physiology. McGraw-Hill Medical, 577. ISBN 0-07-144040-2. 
  3. Gainer JV, Morrow JD, Loveland A, King DJ, Brown NJ (October 1998). "Effect of bradykinin-receptor blockade on the response to angiotensin-converting-enzyme inhibitor in normotensive and hypertensive subjects". N. Engl. J. Med. 339 (18): 1285–92. PMID 9791144[e]
  4. Morimoto T, Gandhi TK, Fiskio JM, et al (June 2004). "Development and validation of a clinical prediction rule for angiotensin-converting enzyme inhibitor-induced cough". J Gen Intern Med 19 (6): 684–91. DOI:10.1111/j.1525-1497.2004.30016.x. PMID 15209608. PMC 1492376. Research Blogging.
  5. Schneider L, Lumry W, Vegh A, Williams AH, Schmalbach T (August 2007). "Critical role of kallikrein in hereditary angioedema pathogenesis: a clinical trial of ecallantide, a novel kallikrein inhibitor". J. Allergy Clin. Immunol. 120 (2): 416–22. DOI:10.1016/j.jaci.2007.04.028. PMID 17559913. Research Blogging.