Age

18–75

Sex

ALL

Healthy volunteers

Not accepted

Acute exacerbation of chronic obstructive pulmonary disease
Untreated obstructive sleep apnea
Restrictive (total lung capacity\<60% predicted) lung disease
Portal hypertension
Chronic liver disease
Transaminase increased to normal line more than 3 times; total bilirubin increased 2 times more than the upper limit of the normal value
Left-sided or unrepaired congenital heart disease
Patients with other serious heart diseases
Patients with 1, 2, 4 and 5 categories of pulmonary hypertension
Unable to complete the 6 minutes walk test
Patients receiving other endothelin receptor antagonists
No cooperation to complete

Study of Bosentan in the Treatment of Stable Severe Chronic Obstructive Pulmonary Disease Patients