Systemic and pulmonary oxidative stress after single-leg exercise in COPD.
BACKGROUND
Our aim for this study was to disentangle the contribution of muscular vs pulmonary oxidative stress during endurance exercise in patients with COPD.


METHODS
Fifteen COPD patients and 10 healthy age-matched control subjects performed a continuously submaximal single-leg ergometer test (40% of peak workload) for 20 min or until they stopped (muscle endurance [Tlim]). Venous blood, urine samples, and exhaled breath condensate were sampled before, immediately after, and 2 h after exercise.


RESULTS
Tlim was lower in COPD patients than in control subjects (p < 0.01). No exercise-induced systemic inflammation (ie, no raised levels of interleukin-6 or tumor necrosis factor-alpha) was found in the groups. Urinary malondialdehyde and uric acid levels (p < 0.05) were increased in COPD patients, whereas erythrocyte oxidized glutathione/reduced glutathione levels tended to be increased in COPD patients compared with control subjects after exercise (p = 0.08). Despite the relatively low cardioventilatory response to this localized muscle exercise, hydrogen peroxide levels in breath condensate significantly increased in COPD patients (p < 0.01). Nuclear factor kappaB DNA-binding activity of p50 in peripheral blood monocytes was elevated after exercise in both COPD patients (p < 0.01) and control subjects (p < 0.05), whereas p65 protein levels were not altered.


CONCLUSIONS
COPD patients showed increased pulmonary and systemic oxidative stress after localized leg muscle exercise compared with healthy control subjects, without evidence of increased levels of systemic inflammation.
Mercken
Evi M
EM
Department of Respiratory Medicine, Maastricht University, Maastricht, the Netherlands. Electronic address: e.mercken@pul.unimaas.nl.
Gosker
Harry R
HR
Department of Respiratory Medicine, Maastricht University, Maastricht, the Netherlands.
Rutten
Erica P
EP
Centre for Integrated Rehabilitation Organ Failure, Horn, the Netherlands.
Wouters
Emiel F
EF
Centre for Integrated Rehabilitation Organ Failure, Horn, the Netherlands; Department of Respiratory Medicine, Maastricht University, Maastricht, the Netherlands.
Bast
Aalt
A
Department of Pharmacology and Toxicology, Maastricht University, Maastricht, the Netherlands.
Hageman
Geja J
GJ
Department of Health Risk Analysis and Toxicology, Maastricht University, Maastricht, the Netherlands.
Schols
Annemie M
AM
Department of Respiratory Medicine, Maastricht University, Maastricht, the Netherlands.
D015992:Body Mass Index; D016552:Ergometry; D015444:Exercise / Q000502:physiology*; D017079:Exercise Tolerance; D005221:Fatigue / Q000503:physiopathology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007249:Inflammation / Q000503:physiopathology; D007866:Leg / Q000502:physiology*; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology; D010807:Physical Endurance; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012016:Reference Values