FIGURE 1.

The RAS in 1965. Angiotensinogen, or renin substrate, is a plasma protein synthesised, like other α‐globulins, by the liver. Renin is synthesised in the juxtaglomerular cells of the kidney and secreted into the renal blood vessels and then into the systemic circulation. There renin cleaves a decapeptide, angiotensin I, from renin substrate. This peptide has little or no biological activity and is a substrate for several plasma peptidases, one of which, the dipeptidyl carboxypeptidase ACE, forms the octapeptide, angiotensin II. This peptide was the only fragment of angiotensin I with biological activity as a vasopressor agent and a stimulator of aldosterone release. Subsequent cleavage of angiotensin II into smaller fragments by other plasma peptidases yields biologically inactive peptides