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Myogenesis

Volume 798 of the series Methods in Molecular Biology pp 245-264

Date:

In Vivo Measurement of Muscle Protein Synthesis Rate Using the Flooding Dose Technique

  • Marta L. FiorottoAffiliated withDepartment of Pediatrics, USDA/ARS Children’s Nutrition Research Center, Baylor College of Medicine Email author 
  • , Horacio A. SosaJr.Affiliated withDepartment of Pediatrics, USDA/ARS Children’s Nutrition Research Center, Baylor College of Medicine
  • , Teresa A. DavisAffiliated withDepartment of Pediatrics, USDA/ARS Children’s Nutrition Research Center, Baylor College of Medicine

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Abstract

Skeletal muscle mass is determined by the balance between rates of protein synthesis and degradation. Protein synthesis rates can be measured in vivo by administering an amino acid as a tracer that is labeled with an isotope (radioactive or stable) of C, H, or N. The rate at which the labeled amino acid is incorporated into muscle protein, as a function of the amount of labeled amino acid in the precursor pool at the site of translation, reflects the rate of protein synthesis. There are a number of approaches for performing this measurement depending on the question being addressed and the experimental system being studied. In this chapter, we describe the “flooding dose” approach using l-[3H]-phenylalanine as the tracer and that is suitable for determining the rate of skeletal muscle protein synthesis (total and myofibrillar proteins) over an acute period (ideally less than 30 min) in any size animal; details for working with mice are presented. The method describes how to administer the tracer without anesthesia, the tissue collection, and the preparation of muscle and blood samples for analysis of the tracer and tracee amino acids in the precursor pool and in muscle proteins.

Key words

Protein synthesis Translation Protein degradation Skeletal muscle Amino acid tracer Phenylalanine