Clinical and functional data of all participants
| Never-smokers | Smokers with normal lung function | COPD patients | |
| Subjects | 7 | 29 | 23 |
| Age yrs | 56±6.7 | 60±1.7 | 65±1.8 |
| Male/female | 6/1 | 27/3 | 22/1 |
| Smoking history pack-yrs | 0 | 37±3.3 | 46±3.1* |
| FEV1 % pred | 97±6 | 92±2.3 | 58±2.4** |
| FEV1/FVC % | 77±2 | 75±0.9 | 55±1.9** |
Data are presented as n or mean±sem. COPD: chronic obstructive pulmonary diease; FEV1: forced expiratory volume in one second; % pred: % predicted; FVC: forced vital capacity. *: p<0.05 for COPD patients versus smokers with normal lung function; **: p<0.01 for COPD patients versus smokers with normal lung function and never-smokers.