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.
Laboratoire de Physiologie des Interactions, Service Central de Physiologie Clinique, Hôpital Arnaud de Villeneuve, 34295 Montpellier Cedex 5, France. christelle_koechlin@hotmail.com
Christelle
C
Koechlin
Annabelle
A
Couillard
David
D
Simar
Jean Paul
JP
Cristol
Hélène
H
Bellet
Maurice
M
Hayot
Christian
C
Prefaut
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