BACKGROUND & AIMS: We tested the effects of branched chain-enriched,
aromatic-deficient amino acids with insulin to correct the altered protein
turnover as well as phenylalanine (Phe) and leucine (Leu) rate of appearance in
compensated cirrhotics and controls.
METHODS: Phe and Leu tracers were infused both before and following intravenous
amino acid administration with insulin and euglycemic clamp.
RESULTS: In cirrhosis, fasting whole-body protein synthesis and protein
degradation were normal; Phe rate of appearance was greater (P<0.05), whereas Leu
rate of appearance/Phe rate of appearance ratio was approximately 35% less than
in controls (P<0.001). Following the infusion, protein synthesis did not increase
(+1% +/ 5% [NS] vs. +21% +/- 5% [P<0.05] in controls); protein degradation was
more suppressed, whereas protein balance increased normally. Total Phe rate of
appearance (0.91 +/- 0.13 micromol x kg-1 x min-1) and Leu/Phe disposal ratio
(3.53 +/- 0.36) were nearly normalized (fasting controls, 0.68 +/- 0.07 micromol
x kg-1 x min-1 and 2.87 +/- 0.14 micromol x kg-1 x min-1, respectively; P>0.05).
However, Leu/Phe endogenous rate of appearance ration remained approximately 50%
less (1.56 +/- 0.31 vs. 2.87 +/- 0.14; P<0.004) than in controls.
CONCLUSIONS: Following this combined infusion in cirrhosis, net protein
deposition increased normally despite a blunted response of protein synthesis.
Phe and Leu to Phe peripheral disposal were near normalized; however
