Objective: To analyze the end product enrichment of the stable isotope labeled amino acid in different time points and the level of catabolism of different protein dose groups under the infusion state of the labeled amino acid in the study of amino acid metabolic kinetics, supplying the data support for the the setting of sampling time in the study of the physiological requirement of protein and amino acid.
Method: Twenty subjects were divided into two groups and were supplied two different doses of protein, all subjects were administered the 13C-leucine for 3 hours by the left basilic vein at 12:00 on day 6 and respired air samples were collected per 15 minutes during the last 30 minutes of infusion, analyzing the 13C enrichment difference at three time points and the 13CO2 production rate of the two dietary protein dose groups to determine whether 13C enrichment was stable or not and how the dietary protein dose influence the 13CO2 production rate.
Result: The difference of 13C enrichment is not significant at three time points for every group subjects (P > 0.05), the 13CO2 production rate of the protein dose group of 0.89 g/kg/d was significantly higher than that of the protein dose group of 0.89 g/kg/d (P < 0.05).
Conclusion: It was suggested that determine one specific time point were determined to compare the metabolic kinetics changes of the different protein and amino acid dose groups, when the physiological requirement of protein and amino acid was explored, and the catabolism level in the bigger dose group was higher than that in the smaller dose group.