Angiotensin II

Angiotensin II is a peptide hormone that constricts blood vessels and stimulates aldosterone release. It is a central effector of the renin–angiotensin system, regulating blood pressure and fluid balance.

Renin–angiotensin system: A hormonal system that regulates blood pressure, sodium balance, and extracellular fluid volume. Angiotensin II is its principal vasoconstrictor and aldosterone-stimulating effector.
Angiotensinogen: A liver-produced plasma protein that serves as the precursor for angiotensin peptides. It is the starting substrate from which the pathway ultimately produces angiotensin II.
Angiotensin-converting-enzyme inhibitor: A drug that inhibits angiotensin-converting enzyme, reducing angiotensin II formation and slowing bradykinin breakdown. This drug class lowers the hormone’s production rather than blocking its receptor.
Hypertension: Persistently elevated arterial blood pressure that increases the risk of cardiovascular and kidney disease. Angiotensin II can raise pressure through vasoconstriction and increased sodium retention.
Angiotensin-converting enzyme: An enzyme that converts angiotensin I into angiotensin II and also breaks down bradykinin. It generates angiotensin II from its circulating precursor.
Renin: A protease released mainly by kidney juxtaglomerular cells that cleaves angiotensinogen. Renin initiates the pathway that supplies angiotensin II’s immediate precursor.
Angiotensin II receptor blocker: A drug that blocks angiotensin II type 1 receptors, reducing many effects of the hormone. These drugs inhibit receptor signaling while leaving angiotensin II production largely intact.
Heart failure: A clinical syndrome in which the heart cannot meet the body’s demands without elevated filling pressures. Chronic angiotensin II signaling can worsen fluid retention and cardiac remodeling in this syndrome.
Angiotensin II receptor: A G protein-coupled receptor family through which angiotensin II produces most of its effects. These receptors transmit the hormone’s effects in blood vessels, adrenal glands, and other tissues.
Angiotensin I: A decapeptide produced when renin cleaves angiotensinogen. This precursor is converted directly into angiotensin II by angiotensin-converting enzyme.

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