Nutritional effects of branched-chain amino acids on injured rats in total parenteral nutrition.

In this study, we investigated the optimal contents of branched-chain amino acids (BCAA) in a balanced amino acid infusion in laparotomized rats. The BCAA contents of four infusion solutions used were prepared to 22, 31, 40, and 49% of total amino acids, respectively. The amounts of essential amino acids except for BCAA were equal in all the solutions. Rats weighing about 240 g were infused with about 200 mg of nitrogen and 10 g of glucose daily for 7 days and evaluated for body weight change, nitrogen balance, plasma and urinary amino acid levels, and plasma constituent levels. The body weights of all the groups were approximately maintained during the infusion period. The nitrogen balance of the BCAA-31 group was more positive than that of the BCAA-22 group and was not different from those of the BCAA-40 and BCAA-49 groups. Plasma total-protein level of the BCAA-31 group was higher than that of the BCAA-22 group and was equal to those of the BCAA-40 and BCAA-49 groups. Even when the BCAA content in an amino acid infusion was increased, no abnormal elevation was observed in plasma BCAA levels. There were no differences in the other nutritional parameters among the four infusion groups. These results suggest that the BCAA contents in an amino acid infusion are enough at 31% of total amino acids for this injured rat model.