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  • Sartan-AT1 receptor interactions: in vitro evidence for insurmountable antagonism and inverse agonism.

Sartan-AT1 receptor interactions: in vitro evidence for insurmountable antagonism and inverse agonism.

Molecular and cellular endocrinology (2008-07-16)
I Van Liefde, G Vauquelin
ABSTRACT

Sartans are non-peptide AT(1) receptor antagonists used to treat hypertension and related pathologies. Their effects on the G protein-dependent responses of angiotensin II (Ang II) were the same in vascular tissues and in isolated cell systems. All are competitive but, when pre-incubated, they act surmountably (only rightward shift of the Ang II concentration-response curve) or insurmountably (also decreasing the maximal response). Insurmountable behaviour reflects the formation of tight sartan-receptor complexes; it is often partial due to the co-existence of tight and loose complexes. Their ratio positively correlates with the dissociation half-life of the tight complexes and depends on the sartan: i.e. candesartan>olmesartan>telmisartan approximately equal EXP3174>valsartan>irbesartan>losartan. When AT(1) receptors display sufficient basal activity (in case of receptor over-expression, mutation and, especially, tissue stretching) sartans may also act as inverse agonists. This rather affects long-term, G protein-independent hypertrophic responses leading to cardiovascular remodelling.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Irbesartan, ≥98% (HPLC), powder