Subject demographics
| COPD | Smokers | Nonsmokers | |
| Subjects | 12 | 11 | 7 |
| Age yrs | 67±6.9 | 57±10.8 | 64±15.2 |
| Male/female | 8/4 | 3/8 | 2/5 |
| Smoking history pack-yrs | 55 (13–125) | 34.8 (23–67) | 0 |
| FEV1 % predicted | 70.6±8.8 | 82.8 (13.1 | 104 (19 |
| FEV1/FVC% | 58.9±7.6 | 75.7±6.3 | NA |
Data are presented as n, mean±sd or mean (range). COPD: chronic obstructive pulmonary disease; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; NA: not available.