进食状态下不同时间点血中标记氨基酸浓度和丰度差异性分析

Analysis of Concentration and Enrichment of Labeled Amino Acid in Blood at Different Time Points in Feed State

目的通过示踪剂动态观察蛋白质和氨基酸的代谢变化过程中在同位素丰度达到稳定的平台期时,不同的时间点血液中标记氨基酸的丰度与浓度的变化,以此反映不同时点蛋白质和氨基酸的氧化分解状况。方法选取20名健康成年男性为研究对象,分为2组,以7 d为一个实验周期,给予受试者日常膳食5 d后,第6天经静脉滴注给予稳定同位素13C标记的亮氨酸,持续3 h。在输液结束前的30 min内每隔15 min取一次血液样品,测定血样中亮氨酸的浓度与13C的丰度值,并比较各时点丰度及浓度的差异性。结果二组受试者3个时间点亮氨酸的浓度与13C丰度值之间的差异无统计学意义。结论在进食状态下持续给予受试者稳定同位素的过程中,不同时间点机体蛋白质和氨基酸的氧化分解处于一个相对稳定的状态,可以在此时期内确定一个同一的时间点来研究机体处于不同的蛋白质和氨基酸营养状态下的各项代谢动力学参数。

Objective To explore the changes of the enrichment and concentration of stable isotope labeled amino acid in blood at the metabolic plateau of protein and amino acid in order to reflect the catabolism level of protein and amino acid. Method Twenty subjects were divided into two groups and were supplied two different doses of protein, the whole experience period was 7 days. All subjects were administered the IsC-leucine for 3 hours by the antecubital vein at the time of 12：130 on day 6 and the blood samples were collected per 15 minutes during the last 30 minutes of the infusion, and the 13C enrichment and concentration of leucine in blood samples were detected and compared. Results The difference of both 13C enrichment and leucine concentration in blood at three time points were not significant for every group subjects （ P 〉 0.05）. Conclusion The oxidation level of protein and amino acid were relative stable at the different time points in the course of stable isotope infusion in the status of feed. The identical time point of the metabolic kinetics parameters under the different nutritional conditions of protein and amino acid should be determined.