IRL-1620

IRL-1620 is a potent and selective endothelin receptor type B (ETB) agonist with a K_i of 16 pM. IC50 & Target:IC50: 16 pM (Endothelin receptor B), 19 μM (Endothelin receptor A)^[1] In Vitro: IRL-1620 is the most potent and specific ligand for the ETB receptor (K_iETA/ K_iETB=120,000) as judged by the K_i values for ETA (19 μM) and ETB (16 PM) receptors^[1].
IRL-1620 is 60 times more selective for the ETB receptor than ET-3 (K_iETA/ K_iETB=1,900)^[1].
In Vivo: IRL-1620 (1-100 nM) induces contractions of the guinea pig trachea. The effective concentration that produces 30 % of 60 mM KCI-induced contraction is estimated to be 28 nM for IRL 1620^[1].
IRL-1620 (1-100 nM) increases cytosolic Ca²⁺ in the vascular endothelium ([Ca]E) with little effect on resting muscle tone, and relaxes the norepinephrine-stimulated tone with an increase in [Ca]E, in rat aorta,^[1].
IRL-1620 improves both acquisition (learning) and retention (memory) on the water maze task and enhances angiogenic and neurogenic remodeling. Rats treated with IRL-1620 significantly reduces the cognitive impairment induced by Aβ. IRL-1620 treatment enhances the number of blood vessels labeled with VEGF compared to vehicle treatment^[2].