The objectives of this study were to 1). examine skeletal muscle
fatty acid oxidation in individuals with varying degrees of adiposity and 2). determine the relationship between skeletal muscle
fatty acid oxidation and the accumulation of long-chain fatty acyl-CoAs. Muscle was obtained from normal-weight [n = 8; body mass index (BMI) 23.8 +/- 0.58 kg/m(2)],
overweight/obese (n = 8; BMI 30.2 +/- 0.81 kg/m(2)), and extremely obese (n = 8; BMI 53.8 +/- 3.5 kg/m(2)) females undergoing abdominal surgery. Skeletal muscle
fatty acid oxidation was assessed in intact muscle strips. Long-chain
fatty acyl-CoA concentrations were measured in a separate portion of the same muscle tissue in which
fatty acid oxidation was determined.
Palmitate oxidation was 58 and 83% lower in skeletal muscle from extremely obese (44.9 +/- 5.2 nmol x g(-1) x h(-1)) patients compared with normal-weight (71.0 +/- 5.0 nmol x g(-1) x h(-1)) and
overweight/obese (82.2 +/- 8.7 nmol x g(-1) x h(-1)) patients, respectively.
Palmitate oxidation was negatively (R = -0.44, P = 0.003) associated with BMI. Long-chain
fatty acyl-CoA content was higher in both the
overweight/obese and extremely obese patients compared with normal-weight patients, despite significantly lower
fatty acid oxidation only in the extremely obese. No associations were observed between long-chain
fatty acyl-CoA content and
palmitate oxidation. These data suggest that there is a defect in skeletal muscle
fatty acid oxidation with extreme
obesity but not
overweight/
obesity and that the accumulation of intramyocellular long-chain fatty acyl-CoAs is not solely a result of reduced
fatty acid oxidation.