Figure 1.

Schematic of muscle protein synthesis rates (MPS) in the basal and postprandial states. Eating a protein meal generally results in a ~2-fold increase in the stimulation of postprandial MPS from basal in healthy muscle. However, a reduced responsiveness of postprandial MPS, or anabolic resistance, to elevated plasma amino acid availability has been detected in older, obese, and adults on maintenance hemodialysis (MHD) (3, 4, 9–13). Muscle disuse is also a common facilitator of anabolic resistance. Hemodialysis patients have been studied on both dialysis and non-dialysis days. Despite peak inflammation (and presumably catabolism) during dialysis, MPS has been shown to be responsive to intravenous elevation of amino acid availability. However, skeletal muscle is overstimulated in the post-absorptive state on a non-dialysis day, which is associated with inflammation and uremic toxins, to induce overt anabolic resistance. Green indicates “healthy” fed-state MPS response, red indicates anabolically resistant fed-state MPS response. ND, non-dialysis day; ID, intra-dialytic.