Des-Arg9-bradykinin

Where it comes from

Made in

Made from bradykinin by carboxypeptidase N in blood and carboxypeptidase M on cells

Sent out by

Wherever bradykinin is made; accumulates in inflamed tissue

Acts on

• Inflamed vessels
• Sensitised pain nerves
• Immune cells

What it does

• Sustains swelling and pain once inflammation is under way ¹
• Builds up when ACE and the other breakdown routes are blocked ¹
• Weak at the B2 receptor bradykinin uses, which is what makes the B1 receptor worth a separate name ¹

In medicine

• No medicine. Several companies developed B1 receptor blockers and took them into phase 1 and phase 2 trials; none was carried further, and why the translation failed is still argued ²
• No clinical test either. It is the receptor rather than the peptide that rises with inflammation, so a blood level would say little ¹

Beyond the body’s own use

• The B1 receptor works in animal models of inflammatory and neuropathic pain, of diabetes and of colitis, which is why those trials were run. The animal work did not fail; the translation did ²
• It was raised in severe COVID-19, but the bradykinin trials in that illness blocked B2 and would have done nothing to it ¹
• Nothing is in trials now and nothing is claimed for the peptide. A B1 blocker that works in people remains the open question ²