Angiotensin 2 Receptor Antagonists

Angiotensin II acts on the type-1 angiotensin II receptor (AT1), a G protein-coupled receptor that couples to Gq, activates phospholipase C and raises cytosolic calcium; it is a key regulator of blood pressure and of sodium retention by the kidney. Drugs in this class occupy that receptor without activating it: the FDA-approved label for telmisartan states that it blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT1 receptor in tissues such as vascular smooth muscle and the adrenal gland, so that its action is independent of the pathways for angiotensin II synthesis. The FDA-approved veterinary label for telmisartan oral solution calls it a selective AT1 receptor blocker with no relevant affinity for other receptors, indicated for the control of systemic hypertension in cats. A drug belongs here because it blocks the receptor, as distinct from an ACE inhibitor, which blocks the enzyme that makes the peptide; the class is the sartans, which UniProt records as strong inhibitors of this receptor.