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 (13)C-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 (13)C 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 (13)C 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 (13)C abundance of 4 major fatty acids in the muscle triglyceride pool is similar; (2) there are no (13)C-label exchanges between fatty acids in the lipid pool; and (3) the incorporation of (13)C-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.