Comparative assessment of the quadriceps and the diaphragm in patients with COPD.
Chronic obstructive pulmonary disease (COPD) and other chronic diseases such as heart failure are accompanied by skeletal muscle alterations that further enhance morbidity and mortality in affected individuals. Several studies have highlighted important structural and biochemical modifications in limb and respiratory muscles in COPD. Reviewing the similarities and differences between the two most studied muscles in COPD, the quadriceps and the diaphragm, may be helpful in providing important clues about the mechanisms underlying muscle changes associated with this disease. Although oxidative stress is present in both muscles, other muscle alterations are clearly distinct between the quadriceps and the diaphragm. For example, the oxidative metabolism varies in opposite directions, the diaphragm exhibiting increased resistance to fatigue while the quadriceps in COPD is characterized by premature fatigability. Differences in muscle phenotypic expression between the diaphragm and the quadriceps indicate that, in addition to systemic factors, the local microenvironment must participate in the reorganization seen in these two skeletal muscles in COPD.
Centre de Recherche, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec, Canada G1V 4G5.
Marc-André
MA
Caron
Richard
R
Debigaré
P N Richard
PN
Dekhuijzen
François
F
Maltais
D002196:Capillaries / Q000503:physiopathology; D003964:Diaphragm / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008931:Mitochondria, Muscle / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009133:Muscular Atrophy; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism / Q000503:physiopathology*; D012132:Respiratory Muscles / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*