A potent ETA receptor antagonist (IC50 1 4 nM) selective for ETA over ETB receptors (IC50 9800 nM) inhibits endothelin-1-induced phosphoinositol hydrolysis in COS-7 cells (pA2 8) reduces blood pressure in a rat model of acute hypoxia-induced pulmonary hypertension (ED50 0 5 mg/kg) reduces femoral artery neointimal lesion size in a mouse model of intraluminal injury decreases BALF pleocytosis as well as pulmonary collagen deposition and fibrosis and improves lung mechanics in a mouse model of bleomycin-induced lung injury at 15 mg/kg