A Novel Stable Isotope Tracer Method to Simultaneously Quantify Skeletal Muscle Protein Synthesis and Breakdown

Crossland, H.; Smith, K.; Atherton, P.J.; et al.

The measurement of muscle protein synthesis/breakdown rates in a single experiment using a stable isotope tracer method has proven to be a considerable design challenge over the years. Here, Wilkinson et al. developed a novel amino acid tracer technique in vitro to quantify muscle protein synthesis/breakdown simultaneously. This study utilized a dual labeled L-methionine (methyl-D₃, -¹³C), which served as both a cellular substrate and donor in the measurement of the synthesis and proteolysis of myofibrillar proteins. The approach was validated with positive and negative protein treatments, with future work aimed to study skeletal muscle protein metabolism in vivo and to possibly extend to alternate species or protein pools.