DeLany 2013 TOS
|Skeletal muscle mitochondrial respiration is lower in African American compared to Caucasian women and is associated with resting metabolic rate and cardiorespiratory fitness.|
Link: Open Access
Event: The Obesity Society
The prevalence of obesity is greater in African American women (AAW) compared to Caucasian women (CW). Lower energy expenditure, particularly lower resting metabolic rate (RMR) is observed in AAW. This low RMR may play a role in the greater obesity in AAW, but reasons for this difference are not known.
We examined skeletal muscle mitochondrial respiration, cardiorespiratory fitness (VO2 peak), and RMR in young (23.8±4.8 y) healthy women. We present data from 20 AAW (22.7±4.0 kg/m2, 62±9 kg) and 22 CW (22.7±3.1 kg/m2; 63±9 kg) matched for BMI and weight. Percutaneous biopsies of the vastus lateralis were obtained following an overnight fast. Mitochondrial respiratory properties were determined in permeabilized muscle fiber bundles by high-resolution respirometry. RMR was measured by indirect calorimetry, and VO2 peak was determined during a graded exercise test.
Basal (State 4; 67±16 vs. 82±18 pmol O2/sec/mg; p<0.015), maximal coupled (State 3; 320±68 vs. 422±65 pmol O2/sec/mg; p<0.001) and uncoupled (State U; 354±76 vs. 483±69 pmol O2/sec/mg; p<0.001) respiration were lower in AAW compared to CW. This corresponded with lower RMR (1259±185 vs 1383±178 kcal/day; p<0.01) and VO2 peak (2007±428 vs 2320±491 ml/min; p< 0.03) in AAW. When combining groups, State 4, State 3 and State U respiration correlated positively with RMR (r=0.44, p<0.01; r=0.39, p<0.03; r=0.40, p<0.02) and VO2 peak (r=0.54, p<0.001; r=0.48, p<0.002; r=0.48, p<0.003).
In summary, RMR and VO2 peak were lower in these young, lean AWW compared with matched CW. Skeletal muscle mitochondrial respiration was also lower in AWW and was associated with RMR and VO2 peak. These data suggest that differences in skeletal muscle mitochondrial respiration are related to the lower metabolic rate in AAW and may be related to the increased risk of weight gain in AA women.
Labels: MiParea: Respiration Pathology: Obesity
Organism: Human Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue
Coupling state: LEAK, OXPHOS