Oxidation of palmitate by human skeletal muscles in vitro. Method and normal values

The conditions of determination of the in vitro incorporation rate of palmitate-carbon into CO2 in human skeletal muscles were studied. Muscle biopsies were taken from 25 patients with nonmuscular diseases and incubated in a metabolic shaker with KRP as medium and palmitate as substrate. Substrate saturation was achieved beyond a palmitate concentration of 2.5 mmol/1, and the incorporation rate was linear with time for 2 hr. The activity of 3-hydroxy-acyl-CoA-dehydrogenase (ACDH), an enzyme involved in the beta-oxidation, was also determined. Both the incorporation rate of palmitate-carbon into CO2 and the activity of ACDH were higher in the leg muscles than in the abdominal muscles. Significant positive correlations were found between the incorporation rate of palmitate-carbon into CO2 and the ACDH activity, and between the incorporation rate and the phospholipid concentration in muscles. These correlations indicate that this in vitro system is valid for evaluation of the metabolism of fatty acids in skeletal muscle tissue.