TOPICS: Pulmonary hypertension drugs, relative vasodilation, decreased pulmonary vascular resistance, endothelin receptor antagonists, bosentan, hepatotoxicity, pde 5 inhibitors, decreased cgmp breakdown, increased cgmp, increases nitric oxide, sildenafil, erectile dysfunction, nitroglycerin, prostacyclin analogs, pgi2, jaw pain, flushing, epoprostenol, iloprost