Savilov P N
Biomed Khim. 2014 May-Jun;60(3):364-71. doi: 10.18097/pbmc20146003364.
The effect of three-day course of hyperbaric oxygenation (HBO; 3 atm, 50 min, 1 session per day) on glutamine metabolism in the liver has been investigated in 72 adult albino rats. The content of ammonia, glutamate, glutamine, activity of glutamine synthetase (GS), phosphate-dependent glutaminase (PDG), and glutamate dehydrogenase (GDH) were studied in left (LLL) and median (MLL) lobes of the liver. The course of HBO had an inhibitory effect on all the enzymes studied. Inhibitory effect of hyperoxia on GDH activity persisted up to day 11 after the course of HBO in both lobes of the liver, while decreased glutamate normalized in both lobes. Reduced glutamine concentration normalized to day 4, and the concentration of ammonia and remained elevated for 11 days after the end of hyperoxic exposure. Inhibitory effect of hyperoxia on GS activity in LLL and MLL disappeared on day 4 and day 11 day after the end of the HBO course. PDG activity reduced by HBO in both lobes normalized to the day 4 day after oxygenation; however, on day 11 it selectively decreased in LLL, where simultaneous stimulation of GS activity was also observed. The results demonstrate different sensitivity of liver GS, PDG and GDH of normal rats to the inhibitory effect of HBO. Different dynamics of GS and PDG activity in LLL and MLL of oxygenated rats suggests functional heterogeneity of the glutamine cycle in hepatocytes of liver lobes after HBO.
在72只成年白化大鼠中研究了为期三天的高压氧治疗（HBO；3个大气压，50分钟，每天1次）对肝脏谷氨酰胺代谢的影响。研究了肝脏左叶（LLL）和中叶（MLL）中氨、谷氨酸、谷氨酰胺的含量，谷氨酰胺合成酶（GS）、磷酸依赖性谷氨酰胺酶（PDG）和谷氨酸脱氢酶（GDH）的活性。HBO疗程对所有研究的酶均有抑制作用。高氧对GDH活性的抑制作用在HBO疗程后直至第11天在肝脏的两个叶中持续存在，而两个叶中的谷氨酸降低水平均恢复正常。降低的谷氨酰胺浓度在第4天恢复正常，氨浓度在高氧暴露结束后持续升高11天。高氧对LLL和MLL中GS活性的抑制作用在HBO疗程结束后的第4天和第11天消失。HBO使两个叶中的PDG活性降低，在氧疗后第4天恢复正常；然而，在第11天，LLL中的PDG活性选择性降低，同时也观察到GS活性的刺激。结果表明正常大鼠肝脏的GS、PDG和GDH对HBO的抑制作用具有不同的敏感性。氧疗大鼠LLL和MLL中GS和PDG活性的不同动态表明HBO后肝叶肝细胞中谷氨酰胺循环的功能异质性。
