Is glutamine a 'conditionally essential' amino acid in Duchenne muscular dystrophy?
To determine whether whole body protein kinetics are altered in Duchenne muscular dystrophy (DMD), six 9 +/- 1-year-old children with DMD and five weight and height matched controls, received intravenous infusion of L-[1-(13)C]leucine and L-[2-(15)N]glutamine in the post-absorptive state. Glutamine rate of appearance was approximatly 24% lower in DMD boys than in controls (321 +/- 22 vs 425 +/- 37 micromol kg(-1)h(-1), P< 0.05) resulting from a 32% decrease in glutamine de novo synthesis (230 +/- 21 vs 340 +/- 34 micromol kg(-1)h(-1), P< 0.05). Whereas there was no difference between groups in estimates of protein degradation and synthesis, leucine oxidation rate was 44% higher in DMD boys than in controls (23 +/- 2 vs 16 +/- 2 micromol kg(-1)h(-1), P< 0.05). The data suggest that the dramatic mucle mass loss observed in DMD boys is associated with a) significant protein wasting, since increased leucine oxidation reflects a more negative whole body leucine balance, and b) a significant decrease in glutamine availability in the postabsorptive state. Glutamine might therefore be a 'conditionally essential' amino-acid in DMD.
Hankard
R
R
Nemours Children's Clinic, Jacksonville, Florida, USA.
Mauras
N
N
Hammond
D
D
Haymond
M
M
Darmaun
D
D
D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D008401:Gas Chromatography-Mass Spectrometry; D005973:Glutamine / Q000008:administration & dosage / Q000378:metabolism*; D006801:Humans; D007262:Infusions, Intravenous; D007700:Kinetics; D007930:Leucine / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000378:metabolism*; D014176:Protein Biosynthesis
D005973:Glutamine; D007930:Leucine