Angiotensin-(1-9)

Where it comes from

Made in

Made from angiotensin I by ACE2 and by carboxypeptidase A, mostly in the heart

Sent out by

Rises on ACE inhibitors; reported to rise after heart attack in rats

Acts on

• Heart muscle and fibroblasts
• Vessels

What it does

• Reduces heart thickening and scarring in rats, an effect lost when AT2 is blocked ¹
• A weak vasodilator, working through AT2 rather than through Mas ²
• Quickly cut by ACE to angiotensin-(1-7), which makes it hard to study on its own ²

In medicine

• No medicine and no test. It has never been given to a person
• It is the reason ACE2 is not simply the angiotensin-(1-7) enzyme: ACE2 makes angiotensin-(1-9) from angiotensin I and angiotensin-(1-7) from angiotensin II, and which route dominates depends on what the tissue has to hand ²
• Blood levels are reported in rodents far more than in people, and the assays struggle to separate it from angiotensin I ²

Beyond the body’s own use

• In rats it lowered blood pressure and reduced damage to the heart and vessels, and blocking AT2 abolished that; this is the evidence behind calling it protective ¹
• No human trial has been registered and no analogue has been published; its rapid conversion to angiotensin-(1-7) is part of why ²
• Nothing is claimed for it outside the laboratory