Description
Angiotensins are small peptides derived from angiotensinogen. Several of the known Angiotensins are established endocrine effectors in the regulation of blood pressure, but they are also known to have other functions locally, in several organs and tissues (paracrine) and at the cellular level (autocrine / intracrine). Angiotensin I has no known effector function but it is an immediate precursor of Angiotensin II. Angiotensin II binds AT1 receptors, which promote vasoconstriction, sodium retention, release of aldosterone, release of Arg-vasopressin, cell proliferation, inflammation, fibrosis, anxiety, and cardiac hypertrophy. Angiotensin A and Angiotensin III, also bind AT1 receptors. Angiotensin (1-7) binds a different receptor called MAS-1 which has opposite effects (vasodilation, natriuresis, antiproliferation, NO release, PGE release, and apoptosis). Angiotensin IV binds yet another receptor called AT4 (IRAP), which promotes increase of blood flow, angiogenesis, and natriuresis, and which has also been implicated in memory formation and in the pathogenesis of Alzheimer-s disease. The peptide LVV-hemorphin-7, which is not an angiotensin, also binds the AT4 receptor