FIGURE 7.

Ceramides, but not sphingomyelins, accumulate in skeletal muscle of insulin-resistant obese mice. Mice were fed either a normal chow diet or high fat diet for 12 weeks. Glucose (2 g/kg of lean mass) (A) or insulin (B) (0.75 IU/kg lean mass) tolerance tests were conducted. Lipids were extracted from quadriceps muscle samples and quantified LC-MS/MS (C and D). The most abundant ceramide, Cer(d18:1/18:0), was found to accumulate in quadriceps, in contrast to the two most abundant sphingomyelins (SM36:1 and SM34:1). Values are expressed as means ± S.E., *, p < 0.05; **, p < 0.01; ***, p < 0.001 versus chow diet and n = 4 animals per group.