The liver creates and releases a protein called angiotensinogen. This is then broken up by renin, an enzyme produced in the kidney, to form angiotensin I. This form of the hormone is not known to have any particular biological function in itself but, is an important precursor for angiotensin II.

Do kidneys produce angiotensin?

Thus, it is not surprising that angiotensin II can be produced locally within the kidneys because of the activity of a complete renin-angiotensin system (RAS) expressed along the nephron. In fact, the renal RAS can play an important role in disease.

How is angiotensin secreted?

Angiotensin I is produced by the action of renin (an enzyme produced by the kidneys) on a protein called angiotensinogen, which is formed by the liver. Angiotensin I is transformed into angiotensin II in the blood by the action of angiotensin-converting enzyme (ACE).