Effects of postoperative infusion of branched chain amino acids on nitrogen balance and forearm muscle substrate flux.
A branched chain amino acid (45% BCAA)--enriched solution was compared with a standard amino acid (25% BCAA) solution in a randomized blinded study in eight patients undergoing cystectomy and ileal loop diversion. Solution administration rates were designed to provide 20 kcal/kg/day and 0.26 gm nitrogen/kg/day postoperatively from days 1 to 8. Daily urine creatinine and nitrogen levels were measured. On day 4 during infusion, forearm blood flow was measured by capacitance plethysmography. Arterial and antecubital deep venous blood samples were drawn simultaneously for determinations of glucose, lactate, pyruvate, and amino acids; substrate flux was calculated (mumol/ml/min, uptake = +, release = -). The mean total amino acid flux was significantly improved In the 45% BCAA group (+1.7 +/- 0.4) versus the 25% BCAA group (-0.03 +/- 0.2, P less than 0.05). The mean total BCAA flux was significantly improved in the 45% BCAA group (+1.1 +/- 0.4) compared with the 25% BCAA group (-0.03 +/- 0.2) (P less than 0.02). There were no significant differences between groups in alanine, glutamine, glucose, lactate, or pyruvate forearm flux. The cumulative adjusted 7-day nitrogen balance was -1.4 +/- 7 gm in the 45% BCAA group and -14.2 +/- 4 gm in the 25% BCAA group (NS). the 45% BCAA solution resulted in significant uptake of total amino acid and BCAA into forearm muscle, which was not significantly demonstrated in whole body nitrogen balance studies. Sixty-six percent of the increase in total amino acid forearm flux with use of the 45% BCAA solution was due to the uptake of BCAA even though less leucine was given compared with the 25% BCAA solution.
D000328:Adult; D000368:Aged; D000597:Amino Acids, Branched-Chain / Q000008:administration & dosage* / Q000378:metabolism; D002986:Clinical Trials as Topic; D003404:Creatinine / Q000652:urine; D005542:Forearm; D006801:Humans; D007263:Infusions, Parenteral; D008875:Middle Aged; D009132:Muscles / Q000032:analysis / Q000098:blood supply*; D009584:Nitrogen / Q000378:metabolism* / Q000652:urine; D011184:Postoperative Period; D011897:Random Allocation; D013997:Time Factors; D001749:Urinary Bladder Neoplasms / Q000601:surgery
D000597:Amino Acids, Branched-Chain; D003404:Creatinine; D009584:Nitrogen