谷氨酰胺对烧伤大鼠肠上皮细胞线粒体呼吸功能的影响

目的　研究谷氨酰胺对烧伤大鼠肠上皮细胞线粒体呼吸功能的影响。方法　采用 30 %体表面积 度烧伤大鼠模型 ,随机分成伤前对照 (C)组、普通肠道营养 (EN)组及谷氨酰胺强化的肠道营养 (GL N )组。EN和 GL N组除是否给予谷氨酰胺外 ,其它条件均相同。分离肠上皮细胞线粒体 ,观察烧伤后各组线粒体呼吸控制率 (RCR)、磷氧比 (P/O)、肠黏膜血流量 (IMBF)及肠道氧摄取率 (Oext)的变化。结果　烧伤后各组线粒体 态呼吸率 (ST3)明显下降 , 态呼吸率 (ST4 )升高 ,RCR显著降低。两组相比 ,GL N组变化幅度较小 ,同时其 IMBF和 Oext也明显高于 EN组。结论　严重烧伤后肠黏膜血流量下降 ,肠道 Oext降低 ,肠上皮细胞线粒体呼吸功能受损 ,氧化磷酸化失耦联。 GL N能改善肠道血供 ,增加 Oext,减轻肠上皮细胞线粒体呼吸功能受抑程度。

Effects of enteral supplementation with glutamine on mitochondria respiratory function of intestinal epithelium in burned rats

OBJECTIVE: To investigate the effects of enteral supplementation with glutamine on mitochondria respiratory function of intestinal epithelium in burned rats. METHODS: Wistar rats inflicted with 30% total body surface area (TBSA) full thickness thermal injury were randomly divided into three groups, i.e. burn with enteral nutrition (EN), burn with glutamine treatment (GLN), and normal control (C) groups. Burned rats were infused 732.2 kJ.kg-1.d-1 solution for intravenous nutrition and oral administration, in which the supply energy ratio of glucose, fat and protein was 55:30:15 respectively, glucose was 15.3% and the proportion of calorie to nitrogen was 183:1. The following indices including respiratory control rate (RCR), oxygen extraction (Oext), P/O ratio and intestine mucosal blood flow (IMBF) were measured on postburn days 1, 3, 5, 7, 10. RESULTS: After burn injury, the RCR, Oext, P/O ratio, and IMBF were significant decreased in both EN and GLN groups, but all above indices were markedly increased in GLN group compared to those in EN group. CONCLUSION: After burn injury, the IMBF and Oext were declined, resulting in mitochondria respiratory oxidative dysfunction and phosphorylation discoupling in intestinal epithelium. GLN supplementation appears to be beneficial to improving IMBF, increasing Oext, abating the extent of mitochondria respiration dysfunction, and promoting oxidative phosphorylation.