TY - JOUR
T1 - Mitochondrial electron transport chain function is enhanced in inspiratory muscles of patients with chronic obstructive pulmonary disease
AU - Ribera, Florence
AU - N'Guessan, Benoit
AU - Zoll, Joffrey
AU - Fortin, Dominique
AU - Serrurier, Bernard
AU - Mettauer, Bertrand
AU - Bigard, Xavier
AU - Ventura-Clapier, Renée
AU - Lampert, Eliane
PY - 2003/3/15
Y1 - 2003/3/15
N2 - In chronic obstructive pulmonary disease, inspiratory muscles face increased resistive and elastic workloads and therefore increased energy requirements. The adaptive response of these muscles to this higher energy demand includes increased oxidative enzymes and changes in contractile protein expression but the consequences on mitochondrial function and energy metabolism have not been assessed so far. We investigated the in situ properties of the mitochondria of costal diaphragm and external intercostal muscles using the skinned fiber technique in 9 emphysematous and 11 age-matched control patients. Biopsies obtained during thoracic surgery were placed in an oxygraphic chamber to measure maximal oxygen uptake. We observed that the maximal oxidative capacity of diaphragm and external intercostal muscles increased significantly in the emphysematous group compared with the control group (+135 and +37%, respectively). Significant correlations were found between the maximal oxidative capacity and patients' pulmonary indexes of obstruction (diaphragm: r = -0.637, intercostal: r = -0.667, p < 0.005) and hyperinflation (diaphragm: r = 0.639, p < 0.003, intercostal: r = 0.634, p < 0.01). Slow myosin heavy chain isoform increased in the diaphragm of the emphysematous group, with significant relationships between indexes of obstruction and hyperinflation and activities of biochemical mitochondrial markers. Thus, severe emphysema was associated with increased mitochondrial capacity and efficiency in the inspiratory muscles, supporting an endurance training-like effect.
AB - In chronic obstructive pulmonary disease, inspiratory muscles face increased resistive and elastic workloads and therefore increased energy requirements. The adaptive response of these muscles to this higher energy demand includes increased oxidative enzymes and changes in contractile protein expression but the consequences on mitochondrial function and energy metabolism have not been assessed so far. We investigated the in situ properties of the mitochondria of costal diaphragm and external intercostal muscles using the skinned fiber technique in 9 emphysematous and 11 age-matched control patients. Biopsies obtained during thoracic surgery were placed in an oxygraphic chamber to measure maximal oxygen uptake. We observed that the maximal oxidative capacity of diaphragm and external intercostal muscles increased significantly in the emphysematous group compared with the control group (+135 and +37%, respectively). Significant correlations were found between the maximal oxidative capacity and patients' pulmonary indexes of obstruction (diaphragm: r = -0.637, intercostal: r = -0.667, p < 0.005) and hyperinflation (diaphragm: r = 0.639, p < 0.003, intercostal: r = 0.634, p < 0.01). Slow myosin heavy chain isoform increased in the diaphragm of the emphysematous group, with significant relationships between indexes of obstruction and hyperinflation and activities of biochemical mitochondrial markers. Thus, severe emphysema was associated with increased mitochondrial capacity and efficiency in the inspiratory muscles, supporting an endurance training-like effect.
KW - Diaphragm
KW - Emphysema
KW - Intercostal muscle
UR - http://www.scopus.com/inward/record.url?scp=0037445290&partnerID=8YFLogxK
U2 - 10.1164/rccm.200206-519OC
DO - 10.1164/rccm.200206-519OC
M3 - Article
C2 - 12493645
AN - SCOPUS:0037445290
SN - 1073-449X
VL - 167
SP - 873
EP - 879
JO - American Journal of Respiratory and Critical Care Medicine
JF - American Journal of Respiratory and Critical Care Medicine
IS - 6
ER -