A Study of Oral Nitrate in Adults With Pulmonary Hypertension With Heart Failure and Preserved Ejection Fraction

INCLUSION: * Male or female, 18 years of age or older * PH group: Pulmonary hypertension, hemodynamically defined by a mean PAP ≥ 25 mm Hg, and a TPG \>= 12 at rest or during exercise as demonstrated on a right heart catheterization in the last 10 years * RHC Control group: Normal hemodynamics (mean PAP \< 25 mm Hg, PCWP ≤ 15 mm Hg) on clinical right heart catheterization * Healthy Control group: Healthy patients with no evidence of pulmonary hypertension, respiratory or cardiac disease * Ability to provide written informed consent EXCLUSION: * Use of systemic antibiotics and/or chlorhexidine mouthwash, within the previous three months * Use of immune suppression (chemotherapy, oral prednisone greater than 20mg per day, etc) with in the previous three months * Use of phosphodiesterase-5 inhibitors (tadalafil, sildenafil, etc) within 7 days before study drug administration * Current pregnancy or lactation * Uncontrolled systemic hypertension based on repeated measurement of sitting systolic blood pressure \>185 mm Hg or sitting diastolic blood pressure \>110 mm Hg at screening * Has chronic renal insufficiency as defined by serum creatinine \>3 mg/dL at screening or requires dialytic support * Known history of left ventricular ejection fraction \< 40% by multiple gated acquisition scan (MUGA), angiography, or echocardiography * History of atrial septostomy * Repaired or unrepaired congenital heart disease * Pericardial constriction * Restrictive or constrictive cardiomyopathy * Symptomatic coronary disease with demonstrable ischemia * Addition or change in dosing of hormonal contraception medications (OCP, IUD, Depo-Provera) in the past 4 weeks. * Other severe acute or chronic medical or laboratory abnormality that may increase the risk associated with study participation or investigational product administration, that may interfere with the interpretation of study results and, in the judgment of the investigator, would make the subject inappropriate for entry into this study or would prevent completion of the study * Active participation in other research studies with investigational drugs