Effects of leucine on whole body leucine, valine and threonine metabolism in humans

The kinetic and metabolic effects of leucine was analyzed in normal human subjects that were infused with the amino acid isotope L-[5,5,5-H3]leucine, L-[1-13C]valine and L-[1-13C]threonine. Amino acid isotope infusions in normal human volunteers reduced plasma leucine enrichment and leucine [alpha-ketoisocaproic acid]. Furthermore, the difference between plasma and intracellular leucine enrichments decreased with the expansion of the amino acid pool.