Development of Oral Amino Acid Tracers to Study Protein Turnover in Humans

Previous studies have used a combination of oral L-\[1-13C\]leucine and intravenous labeled L-\[5,5,5-2H3\]leucine to assess the acute postprandial changes in whole-body protein turnover (12, 19). Intravenous and dietary-labeled amino acid tracers have also been used in tandem to assess rates of myofibrillar protein synthesis in response to bolus protein ingestion and resistance exercise (46). By validating whole-body net balance to myofibrillar protein synthesis, our proposed multi-tracer approach will develop minimally invasive models to study protein turnover in a variety of populations in which traditional infusions and/or repeated blood samples are not possible (i.e. pediatric, free-living populations).