Postprandial increase in AA plasma levels are sufficient to stimulate muscle specific and total protein accretion in vitro

Abstract

Skeletal muscle cell lines have been applied to model muscle growth in vitro. In this study we investigated whether specific amino acids (AA), at concentrations as they appear post‐prandially, are sufficient to directly stimulate muscle specific and total protein accretion in vitro. Myoblasts were cultured in modified DMEM containing 1g/L glucose, 1% FBS and physiological AA levels. Supplementation during differentiation consisted of a mixture of AA at concentrations observed in plasma following consumption of 20g whey protein, which stimulated muscle protein synthetic rate (Pennings et al., 2010). The AA in the mixture were previously identified based on their capacity to stimulate myofibrillar protein accretion in differentiating myoblasts. In contrast to stimulation with any of the single AA, differentiation in the presence of the AA mixture increased creatine kinase activity, myosin heavy chain and myosin light chain 1 levels, as well as total protein accretion. These in vitro findings were in line with in vivo increases in protein synthesis rate and reveal synergistic effects of individual anabolic‐acting AA on general en muscle specific protein accretion.