Reduced amino acid availability inhibits muscle protein synthesis and decreases activity of initiation factor eIF2B

Reduced amino acid availability inhibits muscle protein syn-thesis and decreases activity of initiation factor eIF2B. Am J Physiol Endocrinol Metab 284: E488–E498, 2003; 10.1152/ ajpendo.00094.2002.—We have examined the effect of a he-modialysis-induced 40 % reduction in plasma amino acid con-centrations on rates of muscle protein synthesis and breakdown in normal swine. Muscle protein kinetics were measured by tracer methodology using [2H5]phenylalanine and [1-13C]leucine and analysis of femoral arterial and ve-nous samples and tissue biopsies. Net amino acid release by muscle was accelerated during dialysis. Phenylalanine utili-zation for muscle protein synthesis was reduced from the basal value of 45 8 to 25 6 nmol min1 100 ml leg1 between 30 and 60 min after start of dialysis and was stim-ulated when amino acids were replaced while dialysis con