Dysregulated Renin–Angiotensin–Aldosterone System Contributes to Pulmonary Arterial Hypertension

Rationale: Patients with idiopathic pulmonary arterial hypertension (iPAH) often have a low cardiac output. To compensate, neurohormonal systems such as the renin–angiotensin–aldosterone system (RAAS) and the sympathetic nervous system are up-regulated, but this may have long-term negative effects on the progression of iPAH.Objectives: Assess systemic and pulmonary RAAS activity in patients with iPAH and determine the efficacy of chronic RAAS inhibition in experimental PAH.Methods: We collected 79 blood samples from 58 patients with iPAH in the VU University Medical Center Amsterdam (between 2004 and 2010) to determine systemic RAAS activity.Measurements and Main Results: We observed increased levels of renin, angiotensin (Ang)I, and AngII, which were associated with disease progression (P < 0.05) and mortality (P < 0.05). To determine pulmonary RAAS activity, lung specimens were obtained from patients with iPAH (during lung transplantation, n = 13) and control subjects (during lobectomy or pneumonectomy ...