A-192621 is a potent, nonpeptide, orally active and selective endothelin B (ETB) receptor antagonist with an IC50 of 4.5 nM and a Ki of 8.8 nM. The selectivity of A-192621 is 636-fold higher than ETA (IC50 of 4280 nM and Ki of 5600 nM). A-192621 promotes apoptosis in PASMCs. A-192621 alos causes elevation of arterial blood pressure and an elevation in the plasma ET-1 level[1][2][3].

A-192621 (1-100 μM; 48 hours; PASMCs) treatment markedly reduces the cell viability of PASMCs in a dose-dependent manner[2].A-192621 (1-100 μM; 48 hours; PASMCs) treatment significantly increases the caspase-3/7 activity and cleaved caspase-3 expression in PASMCs. A-192621 induces apoptosis in a dose-dependent manner and increases the cells' susceptibility to apoptosis by Doxorubicin treatment[2]. Cell Viability Assay[2] Cell Line: Pulmonary arterial smooth muscle cells (PASMCs) with Doxorubicin

A-192621 (30-100 mg/kg; oral administration; daily; for 3 days; male Sprague-Dawley rats) treatment inhibits both dilatory and pressor responses induced by S6c mediated by ETB with an ED50 value of 30 mg/kg, and failed to inhibit the ET-1-induced pressor response mediated by ETA. A-192621 alone causes elevation of arterial blood pressure and an elevation in the plasma ET-1 level in the conscious normotensive rat[3]. Animal Model: Male Sprague-Dawley rats (250-350 g)[3]

[1]. Wu-Wong JR, et al. Pharmacology of endothelin receptor antagonists ABT-627, ABT-546, A-182086 and A-192621: in vitro studies. Clin Sci (Lond). 2002 Aug;103 Suppl 48:107S-111S. [2]. Sakai S, et al. Antagonists to endothelin receptor type B promote apoptosis in human pulmonary arterial smooth muscle cells. Life Sci. 2016 Aug 15;159:116-120. [3]. Wessale JL, et al. Pharmacology of endothelin receptor antagonists ABT-627, ABT-546, A-182086 and A-192621: ex vivo and in vivo studies. Clin Sci (Lond). 2002 Aug;103 Suppl 48:112S-117S.