Incorporation of [¹⁴C]Leucine into Human Skeletal Muscle Protein in a Cell-Free System as a Measure of Protein Synthesis

Influence of Stress Hormones

Abstract

There is a strong need for techniques to assess human muscle protein synthesis by repeated sampling to follow the course of physiological and pathophysiological events affecting protein metabolism. Here protein synthesis in human skeletal muscle was studied by the incorporation of [¹⁴C] leucine into protein in a cell-free system. Healthy male volunteers (n=20) received a 6-h infusion of either saline, adrenaline, or a triple-hormone combination of adrenaline, cortisol, and glucagon after an overnight fast. Percutaneous muscle biopsies were taken before and after the infusion. The in vitro incorporation rate per mg of DNA decreased by 11.2±3.6% in the adrenaline group (p<0.05) and by 12.3±3.4% in the triple-hormone group (p<0.01) as compared with the basal preinfusion values. No significant change was seen in the control group. The technique presented offers several advantages and the use of it is advocated in combination with other methods to cover several aspects of muscle protein biosynthesis.