Abstract
Introduction: Recent studies have shown that polymorphisms of the angiotensin-converting enzyme (ACE) gene are closely associated with pulmonary disorders.The aim of this study was 1) to investigate the impact of ACE gene polymorphism on exercise tolerance 2) to determine whether a relationship exists between oxygen responses and differential genotype (DD, DI or II).
Methodology: Twenty-four COPD patients [FEV1=51±2.4%pred] exhibiting exercise-induced desaturation performed endurance exercise at 60% of their maximal workload in two randomised conditions: normoxia and hyperoxia. ACE genotype was determined for each patient. Endurance time (Tlim), dyspnoea, cardiac output (CO) and arterio-venous difference in oxygen (AVD) were compared.
Results: In normoxia, Tlim was greater for DI than DD (1168 vs 541s; p<0.05). Oxygen supply improved performance in both groups, but DI again exhibited better endurance than DD (1313 vs 1132s; p=0.01). This better exercise capacity in DI was associated with a greater AVD and decreased CO for comparable oxygen uptake.
Although O2 significantly increased Tlim in two-thirds of patients (R+) and significantly decreased it in about one-third (R-), R+ and R- proportion was comparable in the two genotype groups (chi2=0.52, p=0.46).
Conclusion: This study showed that I-allele was associated with better endurance performance. Although DD and DI increased performance with oxygen, responses were associated with differential consequences on cardiovascular and peripheral muscle adaptations. However, ACE polymorphism could not be related to positive or negative oxygen responses.
- © 2011 ERS