Bradykinin is a 9-amino acid peptide that dilates blood vessels and consequently reduces blood pressure by inducing the release of prostacyclin, nitric oxide, and endothelium-derived hyperpolarizing factor. It also contracts non-vascular smooth muscle in the bronchus and gastrointestinal tract, increases vascular permeability, and is involved in the mechanism of pain mediation. The discovery of bradykinin-potentiating peptides from snake venom led to the discovery of a class of highly-effective anti-hypertensive drugs, the ACE inhibitors, which have been shown to prevent angiotensin-converting enzyme’s inactivation of bradykinin.
