Blood ammonia increases during exercise, and it has been suggested that this increase is both a central and peripheral fatigue factor. Although green tea catechins (GTCs) are known to improve exercise endurance by enhancing lipid metabolism in skeletal muscle, little is known about the relationship between ammonia metabolism and the endurance-improving effect of GTCs. Here, we examined how ammonia affects endurance capacity and how GTCs affect ammonia metabolism in vivo in mice and how GTCs affect mouse skeletal muscle and liver in vitro. In mice, blood ammonia concentration was significantly negatively correlated with exercise endurance capacity, and hyperammonaemia was found to decrease whole-body fat expenditure and fatty acid oxidation–related gene expression in skeletal muscle. Repeated ingestion of GTCs combined with regular exercise training improved endurance capacity and the expression of urea cycle–related genes in liver. In C2C12 myotubes, hyperammonaemia suppressed mitochondrial respiration; however, pre-incubation with GTCs rescued this suppression. Together, our results demonstrate that hyperammonaemia decreases both mitochondrial respiration in myotubes and whole-body aerobic metabolism. Thus, GTC-mediated increases in ammonia metabolism in liver and resistance to ammonia-induced suppression of mitochondrial respiration in skeletal muscle may underlie the endurance-improving effect of GTCs.

运动过程中血氨增加，并且已经表明这种增加既是中央疲劳也是外周疲劳因素。尽管已知绿茶儿茶素（GTC）通过增强骨骼肌中的脂质代谢来改善运动耐力，但对氨代谢与GTC的耐力改善作用之间的关系知之甚少。在这里，我们研究了氨如何在小鼠体内影响耐力能力以及GTC如何在体内影响氨代谢以及GTC在体外如何影响小鼠骨骼肌和肝脏。在小鼠中，血氨浓度与运动耐力显着负相关，并且发现高氨血症可以减少全身脂肪消耗和骨骼肌中脂肪酸氧化相关基因的表达。重复摄入GTC并定期运动训练可改善肝脏的耐力和尿素循环相关基因的表达。在C2C12肌管中，高氨血症抑制线粒体呼吸。但是，与GTC的预孵育挽救了这种抑制作用。在一起，我们的结果表明，高氨血症会降低肌管中的线粒体呼吸和全身有氧代谢。从而，