Comparison of different amino acid solutions for total parenteral nutrition in rats

The experiment was undertaken to determine the optimal amino acid solution for total parenteral nutrition (TPN) in 20 rats. Four different amino acid solutions were used, namely A, B, C and D, of which the E/N ratios were in order 0.8, 1.0, 2.0 and 3.0. TPN was introduced to rats of non-operated and operated groups, using these amino acids. Body weight change, nitrogen balance and plasma and urine aminograms were studied for assessment of the effect. The results were as follows; Non-operated group: Although all groups showed weight gain and positive nitrogen balance, group B with an E/N ratio of 1.0 was the best, followed by C, A then D. Blood aminograms showed markedly elevated levels of Thr in all groups, especially in B, C and D. This may be due to overdosage of Thr for rats. D group had increased urinary loss of Lys, Thr and Glu. These data suggest that B was the best amino acid solution for TPN in the non-operated group. Operated group: A small intestinal bypass operation was performed in rats and TPN was begun after operation. Weight gain and positive nitrogen balance were less than in the non-operated group. The best result was obtained in group C. Marked rise of Thr was observed as in the non-operated group. The typical pattern of postoperative change of aminogram was not seen, i.e., Phe, Met, branched amino acid did not increase. The aminogram of group C was close to the normal pattern. In the operated group, C with an E/N ratio of 2.0 was the optimal amino acid solution.