Bradykininin

Bradykinin is a peptide that is found in the body fluids of mammals. It is a vasodilator, meaning it causes blood vessels to widen, and it also plays a role in inflammation and pain. Bradykinin is part of the kinin-kallikrein system, a group of proteins that regulate blood pressure and blood clotting.

Bradykinin is produced when an enzyme called kallikrein cleaves a larger protein called high molecular weight kininogen. Once formed, bradykinin binds to specific receptors on cells, triggering various responses. Its vasodilatory effects are mediated by its action on endothelial cells, leading to the release of nitric oxide, which relaxes smooth muscle in blood vessel walls.

In the context of inflammation, bradykinin contributes to increased vascular permeability, allowing immune cells and fluid to reach the site of injury or infection. This process is accompanied by pain, as bradykinin sensitizes nerve endings. It is a mediator in inflammatory conditions such as arthritis and is involved in the inflammatory response to burns and other tissue damage.

The body has mechanisms to regulate bradykinin levels, including enzymes that break it down. However, dysregulation of the kinin-kallikrein system can contribute to various pathological conditions, including hypertension and inflammatory diseases. Research continues to explore the therapeutic potential of targeting bradykinin pathways for treating a range of medical conditions.