Lower activity of oxidative key enzymes and smaller fiber areas in skeletal muscle of postobese women.
Muscle fiber morphology and activities of four key enzymes, as well as energy metabolism, were determined in nine normal-weight postobese women and nine matched control subjects. No differences in fiber type composition, but a smaller mean fiber area and area of fiber types I and IIb, were found in postobese compared with control subjects (P < 0.05). The activities of beta-hydroxyacyl-CoA dehydrogenase (HADH) and citrate synthase (CS) were 20% lower in postobese than in control subjects (P < 0.05). However, the activities of lactate dehydrogenase and lipoprotein lipase were not significantly different between postobese and control subjects. Basal metabolic rate and respiratory exchange ratio were also similar, but maximal oxygen uptake (VO2 max) tended to be lower in postobese than in control subjects (P = 0.06). When adjustments were made for differences in VO2 max, HADH and CS were not different between postobese and control subjects. In conclusion, these data suggest that smaller fiber areas and lower enzyme activities, i.e., markers of aerobic capacity of skeletal muscle, but not fiber composition, may be factors predisposing to obesity.
Raben
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A
Research Department of Human Nutrition, Center for Food Research, The Royal Veterinary and Agricultural University, DK-1958 Frederiksberg, Denmark.
Mygind
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E
Astrup
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A
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000378:metabolism; D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000033:anatomy & histology; D000328:Adult; D001481:Basal Metabolism; D001794:Blood Pressure; D015992:Body Mass Index; D001835:Body Weight; D002196:Capillaries / Q000033:anatomy & histology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D004038:Diet, Reducing; D005260:Female; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008071:Lipoprotein Lipase / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000201:enzymology*; D018482:Muscle, Skeletal / Q000098:blood supply / Q000201:enzymology*; D009765:Obesity / Q000235:genetics / Q000503:physiopathology*; D010101:Oxygen Consumption; D012016:Reference Values; D012044:Regression Analysis; D015431:Weight Loss / Q000502:physiology*
D015094:3-Hydroxyacyl CoA Dehydrogenases; D007770:L-Lactate Dehydrogenase; D002950:Citrate (si)-Synthase; D008071:Lipoprotein Lipase