Histochemical and morphological characteristics of the vastus lateralis muscle in patients with chronic obstructive pulmonary disease.
OBJECTIVE
In this study, we examined the fiber-type proportions, cross-sectional areas (CSA), and capillarization from needle biopsies of the vastus lateralis muscle in 20 patients with chronic obstructive pulmonary disease (COPD) (FEV1 = 37 +/- 11% predicted, peak VO2 = 13 +/- 4 mL.min-1.kg-1) and nine age-matched normal subjects (peak VO2 = 33 +/- 7 mL.min-1.kg-1). The effects of endurance training on these parameters were also evaluated in 11 of the 20 patients with COPD.


RESULTS
The proportion of Type I fiber was smaller in COPD than normals (34 +/- 14% vs 58 +/- 16 in normals, P < 0.0005) with a corresponding increase in Type IIb fiber (P = 0.015). The CSA of Type I, IIa, and IIab fibers was also smaller in COPD. The capillary to fiber ratio tended to be reduced in patients, but this difference did not reach statistical significance (P = 0.15). The number of capillary contact for Type I, IIa, and IIab fibers was significantly reduced in COPD compared with normal subjects (P < 0.05). When corrected for the CSA, this parameter was similar for both groups. After training, peak VO2 increased by 11% (P < 0.05), the fiber-type proportion remained unchanged, and the CSA of Type I and IIa fibers increased by 31 and 21%, respectively (P < 0.05). Although the number of capillary contact for each fiber types increased with training, the capillary to fiber ratio and the number of capillary contact for the different fiber types relative to their CSA remain unchanged.


CONCLUSIONS
We conclude that in COPD, 1) the vastus lateralis muscle is characterized by a marked decrease in Type I fiber proportion, an increase in Type IIb fiber proportion, a decrease in Type I, IIa, and IIab fiber CSA and by a relatively preserved capillarization; and 2) a 12-wk training program induces a significant increase in Type I and IIa CSA.
Whittom
F
F
Unité de recherche, Institut de Cardiologie et de Pneumologie de Québec, Canada.
Jobin
J
J
Simard
P M
PM
Leblanc
P
P
Simard
C
C
Bernard
S
S
Belleau
R
R
Maltais
F
F
D000368:Aged; D015308:Anaerobic Threshold / Q000502:physiology; D000704:Analysis of Variance; D019412:Anatomy, Cross-Sectional; D001707:Biopsy, Needle; D002196:Capillaries / Q000737:chemistry / Q000473:pathology; D016022:Case-Control Studies; D005080:Exercise Test; D005081:Exercise Therapy; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006651:Histocytochemistry; D006801:Humans; D007773:Lactates / Q000097:blood; D008173:Lung Diseases, Obstructive / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology / Q000534:rehabilitation; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000737:chemistry / Q000648:ultrastructure; D018657:Muscle Fibers, Slow-Twitch / Q000737:chemistry / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000098:blood supply / Q000737:chemistry / Q000473:pathology*; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology
D007773:Lactates; D010100:Oxygen