Effect of Inhaled Albuterol in Pulmonary Hypertension

Inclusion Criteria: * A Mean Pulmonary Artery Pressure \>25mmHg, Pulmonary Vascular Resistance \>3 wood/units and pulmonary arterial wedge pressure \<15mmHg, as documented by right heart catheterization within the last 3 years * Regular use of oral pulmonary vasodilators Exclusion Criteria: * Presence of chronic respiratory disease (as documented by prior lung imaging and pulmonary function tests), cardiovascular disease (as documented by prior echocardiography and/or left heart catheterization), thromboembolic PAH (as documented by pulmonary angiography) * women of childbearing potential who do not use accepted birth- control measures * pregnant and breast-feeding women * respiratory infection within 4 weeks of testing * A systemic systolic arterial BP\> 150 and/or diastolic arterial BP\>100 on the experiment day * A resting O2 saturation of \< 90% * Current smoking * BMI \>35 kg/m2 and/or a diagnosis of obstructive sleep apnea * Use of inhaled or intravenous pulmonary vasodilators