| Nonsmokers | Smokers | COPD | |
| Subjects n | 6 | 7 | 8 |
| Age yrs | 66±5 | 68±7 | 67±9 |
| Tobacco consumption pack-yrs | 0 | 30±3 | 40±8 |
| FEV1 % pred | 92±3 | 90±6 | 68±8 |
| FVC % pred | 94±4 | 93±8 | 87±6 |
| FEV1/FVC % | 89±5 | 87±7 | 63±5 |
| TLC %pred | 90±6 | 88±3 | 97±4 |
| Pa,O2, mmHg | 90±8 | 85±7 | 84±6 |
| Pa,CO2 mmHg | 37±6 | 39±3 | 41±3 |
Data are presented as mean±sem, unless otherwise stated. COPD: chronic obstructive pulmonary disease; FEV1: forced expiratory volume in 1 s; % pred: % predicted; FVC: forced vital capacity; TLC: total lung capacity; Pa,O2: arterial oxygen tension; Pa,CO2: arterial carbon dioxide tension.