Does oxidative stress alter quadriceps endurance in chronic obstructive pulmonary disease?
The role of exercise-induced oxidative stress in the reduced quadriceps endurance of chronic obstructive pulmonary disease (COPD) patients has never been shown. We conducted a randomized, double-blind, and crossover study in which nine severe patients performed localized dynamic quadriceps endurance tests at 40% of maximal strength after oral treatment with the antioxidant, N-acetylcysteine (NAC), and placebo. Venous blood was sampled before, immediately after exercise, and 6 hours later. Endurance time improved by 25% after NAC treatment compared with placebo (p < 0.05). Superoxide anion (oxidant) release by stimulated phagocytes decreased after treatment (p < 0.05). No change in the antioxidant system was observed. Lipid peroxidation, an index of oxidative stress, was significantly increased 6 hours after exercise in the placebo condition (p < 0.05) but not after treatment. Advanced oxidized protein products, another index of oxidative stress, were also increased 6 hours after exercise by 139 +/- 27% in the placebo condition but only by 54 +/- 19% after treatment (p < 0.05). This study shows that NAC treatment in COPD reduced basal disturbance in the prooxidant system, improved endurance time, and prevented exercise-induced oxidative stress. Oxidative stress thus seems to be implicated in the reduced quadriceps endurance of patients with COPD.
Koechlin
Christelle
C
Laboratoire de Physiologie des Interactions, Service Central de Physiologie Clinique, Hôpital Arnaud de Villeneuve, 34295 Montpellier Cedex 5, France. christelle_koechlin@hotmail.com
Couillard
Annabelle
A
Simar
David
D
Cristol
Jean Paul
JP
Bellet
Hélène
H
Hayot
Maurice
M
Prefaut
Christian
C
D000111:Acetylcysteine / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D000284:Administration, Oral; D000368:Aged; D000975:Antioxidants / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D001682:Biological Availability; D018592:Cross-Over Studies; D004311:Double-Blind Method; D016903:Drug Monitoring; D005541:Forced Expiratory Volume; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D018384:Oxidative Stress / Q000187:drug effects; D010807:Physical Endurance / Q000187:drug effects; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000378:metabolism / Q000503:physiopathology; D013848:Thigh; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D013997:Time Factors; D016896:Treatment Outcome; D014797:Vital Capacity
D000975:Antioxidants; D017392:Thiobarbituric Acid Reactive Substances; D000111:Acetylcysteine