Branched-chain Amino Acid Nitrogen Transfer to Alanine In Vivo in Dogs: DIRECT ISOTOPIC DETERMINATION WITH [¹⁵N]LEUCINE

• Text
• PDF

Abstract

To investigate the contribution of branched-chain amino acids as a nitrogen source for alanine in vivo, dogs were infused with l-[15N]leucine, l-[U-14C]leucine, l-[2,3,3,3-2H4]alanine, and d-[6,6-2H2]-glucose. 14C and 15N isotopic equilibrium in plasma leucine, and deuterium enrichment in arterial and femoral plasma glucose and alanine were achieved within 3 h of initiation of the respective isotope infusion in all animals. The average flux of leucine determined by [15N]leucine was 5.4 μmol·kg−1·min−1, whereas using [14C]leucine it was 3.7 μmol·kg−1·min−1. Turnover rates for alanine and glucose were 11.0 and 17.2 μmol·kg−1·min−1, respectively.

Authors

E. Ben Galim, K. Hruska, D. M. Bier, D. E. Matthews, M. W. Haymond