Discrepancy between muscle and whole body protein turnover.

To understand the mechanisms of muscle wasting, muscle protein turnover is measured. Several techniques are available, including whole body protein turnover measurements and incorporation of tracer into mixed muscle protein. In this brief review, we will focus on these techniques. We conclude that whole body measurements cannot be used as a parameter of muscle protein metabolism. It appears that whole body measurements mainly represent splanchnic protein metabolism. Muscle protein synthesis preferably is measured in individual proteins or protein subfractions.