^(13)C蛋氨酸呼气试验评估肝脏线粒体功能

Evaluation of Liver Mitochondrial Function Using ^(13)C-Methionine Breath Test

目的比较甲基13C蛋氨酸(M-met)与1-13C蛋氨酸(L-met)两种不同13C标记的蛋氨酸在正常条件和急性氧化应激下评估线粒体氧化的差异。方法 20名健康男性受试者摄入水溶M-met,给药前后分别收集各时间点的呼气样本。48h后,受试者摄入酒精后30min进行相同的试验。7天后受试者使用L-met作为底物分别在正常条件和摄入酒精后进行呼气试验。结果结果显示正常条件下L-met蛋氨酸呼气试验(Methionine Breath Test,MBT)呼气中13CO2累积排出率(%cum-dose)比M-met MBT略高(P<0.01)。酒精摄入后两种底物在60min和120min时的累积排除率(%cum dose60,%cum dose120)均下降(P<0.01)。而L-met的累积排除率却明显高于M-met(P<0.01)。结论与M-met MBT相比,L-met MBT在评估肝脏线粒体功能方面具有更好的可靠性,因为L-met中更多标记的碳原子进入三羧酸循环。

Objective To explore differences between two differently 13C-labeled methyl-13C-methionine （M-met） and L-methionine-l-13COOH （L-met） in the evaluation of mitochondrial oxidation in basal condi- tions and after an acute oxidative stress. Methods 20 healthy male subjects received M-met which dissolved in water. Breath samples were taken before and after the ingestion of the labeled substrate. Forty eight hours later, subjects underwent the same breath test 30 min after ethanol ingestion. Seven day later, subjects underwent breath test using L-met as substrate, in basal condition and after ethanol ingestion. Results The results showed that the cumulative percentage of 13 CO2 recovered in breath at basal condition during the test period by using L- met was higher than that of using M-met （P 〈 0.01 ）. After ethanol ingestion, the cumulative percentage of 13CO2 was significantly decreased at 60 and 120 rain with both methionines （P 〈 0.01 ）. However, the cumula- tive percentage of 13 CO2 during L-met MBT was significantly higher than that observed during M-met MBT （P〈0.01 ） . Conclusion Compared with M-met, the breath test based on L-met seems to be a greater reliability to assess mitochondrial function because a larger amount of labeled carbon could reaches the Krebs＇ circle.