Angiotensin II receptors

Angiotensin II receptors

Angiotensin II receptors are a group of G-protein coupled receptors. They are an important part of the renin-angiotensin system, involved in signal transduction. In humans angiotensin II receptors have two subtypes: AT1 and AT2 receptors. AT3 receptors have been demonstrated in vitro in mouse cells. AT4 receptor demonstrated in guinea pigs has high affinity for Angiotensin IV [1].

AT1 receptor

Stimulation of AT1 receptor produces vasoconstriction and is pro-inflammatory. Losartan is a selective AT1 antagonist widely used in the treatment of hypertension. Telmisartan is another AT1 receptor blocker, which is also popular as an antihypertensive agent. AT1 receptor is also involved in the stimulation of aldosterone synthesis, cardiac hypertrophy and vascular smooth muscle proliferation.

When stimulated by an agonist, AT1 receptors gets internalized and desensitized. AT1 receptors are present only in minute quantities and are difficult to purify because of their instability. The gene for AT1 receptors have been mapped to chromosome 3q21-3q25.

AT2 receptor

Stimulation of AT2 receptor produces vasodilatation and it is anti-proliferative. AT2 receptor concentration is high in the fetus and neonate, but low in the adult. The exact role of AT2 receptors is still debated. In general the effects seem to be opposite of AT1 receptors, at least in in-vitro studies [2]. Unlike AT1 receptors, AT2 receptors do not get internalized or desensitized on stimulation by agonist.

Reference

1. Singh KD, Karnik SS. Angiotensin Receptors: Structure, Function, Signaling and Clinical Applications. J Cell Signal. 2016 Jun;1(2):111. doi: 10.4172/jcs.1000111. Epub 2016 Apr 8. PMID: 27512731; PMCID: PMC4976824.
2. Lemarié CA et al. The angiotensin II type 2 receptor in cardiovascular disease. J Renin Angiotensin Aldosterone Syst. 2010;11:19-31.