title: Lipofuscin accumulation in the vastus lateralis muscle in patients with chronic obstructive pulmonary disease.
abstract: Exercise-induced oxidative stress has been reported in patients with chronic obstructive pulmonary disease (COPD) and may play a role in muscle fatigue. It is speculated that oxidative stress during exercise originates from the contracting muscles but this has not been documented. The accumulation of lipofuscin, a marker of cellular oxidative damage, was evaluated in the vastus lateralis muscle in 17 patients with COPD and 10 healthy subjects of similar age. Each subject performed a stepwise exercise test up to maximal capacity during which oxygen uptake (VO(2)) was measured. Resting and peak exercise blood gases were also obtained. Two indices of lipofuscin accumulation were used: lipofuscin inclusions/fiber ratio (LI/F) and lipofuscin inclusions/fiber cross-sectional area ratio (LI/CSA). These ratios were also determined for each specific fiber-type. LI/F (P < 0.01) and LI/CSA (P < 0.01) were greater in COPD compared to healthy subjects. LI/F and LI/CSA for all fiber types were also greater in COPD (P < 0.001). In both groups, LI/F (P < 0.001) and LI/CSA (P < 0.01) were higher in type I than in type II fibers. LI/F and LI/CSA did not correlate significantly with resting PaO(2) and SaO(2), peak VO(2), and DeltaPaO(2) and DeltaSaO(2) during exercise (P > 0.05). Increased lipofuscin accumulation, a marker of oxidative damage, was found in the vastus lateralis muscle in patients with COPD compared to healthy subjects. Oxidative damage of muscle tissue may thus be involved in skeletal muscle dysfunction and wasting in COPD.
authors.affiliation: Centre de Recherche, Institut de Cardiologie et de Pneumologie de l'Université Laval, Hôpital Laval, 2725 Chemin Ste-Foy, Ste-Foy, Québec, G1V 4G5 Canada.
authors.forename: Joakim
authors.initials: J
authors.lastname: Allaire
authors.forename: François
authors.initials: F
authors.lastname: Maltais
authors.forename: Pierre
authors.initials: P
authors.lastname: LeBlanc
authors.forename: Pierre-Michel
authors.initials: PM
authors.lastname: Simard
authors.forename: François
authors.initials: F
authors.lastname: Whittom
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Doyon
authors.forename: Clermont
authors.initials: C
authors.lastname: Simard
authors.forename: Jean
authors.initials: J
authors.lastname: Jobin
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D002479:Inclusion Bodies / Q000473:pathology; D008062:Lipofuscin / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism / Q000473:pathology; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism / Q000473:pathology; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology*; D018384:Oxidative Stress; D005082:Physical Exertion; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism* / Q000473:pathology*
chemical_list: D008062:Lipofuscin