RESPONSE OF PHENYLALANINE AND LEUCINE KINETICS TO BRANCHED CHAIN-ENRICHED AMINO-ACIDS AND INSULIN IN PATIENTS WITH CIRRHOSIS

Background & Aims: We tested the effects of branched chain-enriched, a romatic-deficient amino acids with insulin to correct the altered prot ein turnover as well as phenylalanine (Phe) and leucine (Leu) rate of appearance in compensated cirrhotics and controls. Methods: Phe and Le u tracers were infused both before and following intravenous amino aci d administration with insulin and euglycemic clamp. Results: In cirrho sis, fasting whole-body protein synthesis and protein degradation were normal; Phe rate of appearance was greater (P < 0.05), whereas Leu ra te of appearance/Phe rate of appearance ratio was approximate to 35% l ess than in controls (P < 0.001). Following the infusion, protein synt hesis did not increase (+1% +/- 5% [NS] vs. +21% +/- 5% [P < 0.05] in controls); protein degradation was move suppressed, whereas pvotein ba lance increased normally. Total Phe rate of appearance (0.91 +/- 0.13 mu mol . kg(-1). min(-1)) and Leu/Phe disposal ratio (3.53 +/- 0.36) w ere nearly normalized (fasting controls, 0.68 +/- 0.07 mu mol . kg(-1) . min(-1) and 2.87 +/- 0.14 mu mol . kg(-1). min(-1), respectively; P > 0.05). However, Leu/Phe endogenous rate of appearance ratio remained approximate to 50% less (1.56 +/- 0.31 vs. 2.87 +/- 0.14; P < 0.004) than in controls. Conclusions: Following this combined infusion in cir rhosis, net protein deposition increased normally despite a blunted re sponse of protein synthesis. Phe and Leu to Phe peripheral disposal we re near normalized; however, the exaggerated endogenous Phe production was not corrected entirely.