Determination of skeletal muscle triglyceride synthesis using a single muscle biopsy

A novel stable isotopic technique for the determination of triglyceride synthesis in skeletal muscle by using a single muscle biopsy has been developed and evaluated in rats. In previous studies using ¹³C-tracers, muscle triglyceride synthesis is usually determined using at least 2 biopsies, the first of which serves as the baseline sample for the measurement of natural ¹³C abundance. In the present studies, the baseline biopsy has been eliminated by making the use of the isotopic information of a nontraced fatty acid in the muscle triglyceride pool. This is based on the fact that the source and, hence, the natural ¹³C abundance of fatty acids in the same triglyceride pool is similar. To demonstrate and validate the method, a series of rat studies have been conducted to have established that (1) the natural ¹³C abundance of 4 major fatty acids in the muscle triglyceride pool is similar; (2) there are no ¹³C-label exchanges between fatty acids in the lipid pool; and (3) the incorporation of ¹³C-palmitate into muscle triglycerides determined using this technique favorably compared with that determined by the traditional method. This approach makes stable isotope studies possible in which more than 1 muscle biopsy is difficult or impossible. Therefore, it has the potential to facilitate investigation of triglyceride metabolism in the skeletal muscle.