The optimal nitrogen proportion to non-protein calories in normal rats receiving hypocaloric parenteral nutrition

Abstract

The purpose of this study was to determine the optimal ratio of amino acids, in terms of the ratio of non-protein calories to nitrogen (NPC/N ratio), in peripheral parenteral nutrition (PPN). Test solutions that NPC/N ratio is 50, 100, 150 or 200, or amino acid free solution were administered parenterally at a rate of 120 kcal/kg/day for 5 days to normal rats, after which the effects of amino acid on protein metabolism were assessed. Cumulative nitrogen balance increased with a decrease in the NPC/N ratio (with a increase in amino acid dose), but there were no statistically significant differences between group NPC/N: 50, group NPC/N: 100, and group NPC/N: 150. The protein synthesis rate in the liver increased with a decrease in the NPC/N ratio, and the value in group NPC/N: 200 and group NPC/N: 150 was significantly lower than that in group NPC/N: 50. However, in group NPC/N: 50, the levels of serum urea nitrogen (SUN) and serum branched chain amino acids (BCAA) were high, suggesting the excessive administration of amino acids. Based on the above findings, the optimal NPC/N ratio is estimated to be about 100 (50 g as amino acids), when the intravenous solution is administered at the anticipated daily dose in clinical use (1000 kcal/day).