ACE and pulmonary arterial hypertension: In the hypoxic rat model both captopril, an angiotensin converting enzyme inhibitor, and losartan have been shown to prevent the haemodynamic and structural changes of pulmonary hypertension without inhibiting acute hypoxic vasoconstriction [13,31] In addition, right ventricular remodelling in the chronically hypoxic rat is associated with increased angiotensin converting enzyme expression and activity [32].