烧伤早期大鼠心肌线粒体DNA4.8kb大片段缺失的检测及其意义

Myocardial injury in rats induced by 4.8 kb deletion of mtDNA at the early stage of severe burn

目的 观察严重烧伤早期大鼠心肌组织线粒体DNA (mtDNA) 4.8kb大片段缺失的规律 ,探讨线粒体参与烧伤后“休克心”形成的基本机制。方法 SpragueDawley(SD)大鼠 3 6只随机分为假烫伤组、3 0 %TBSAⅢ度烫伤 1、3、6、12、2 4h组 ,半定量PCR法检测烧伤前后心肌线粒体DNA缺失率 ,并测定各组大鼠心肌线粒体中ATP、ADP、AMP以及血清中肌钙蛋白I(TnI)含量变化。结果 ①大鼠烧伤后 1、3、2 4h分别发生了线粒体DNA(mtDNA)的部分或全部 4 8kb大片段缺失。②大鼠烧伤后 1、3、6、2 4h时心肌线粒体中ATP含量下降 ,结果有显著性意义 (P <0 0 5 ,P <0 0 1)。③大鼠烫伤后血清中TnI含量急剧上升 ,至伤后 6h达最高峰 ,变化有显著性意义 (P <0 0 5 ,P <0 0 1)。结论 烧伤早期心肌mtDNA发生了严重缺失 ,可能诱发线粒体氧化磷酸化障碍 ,促进了烧伤早期心肌损伤。

Objective To investigate the 4.8 kb deletion of mtDNA in rat myocardial tissues at the early stage of severe burn and identify the roles of mitochondria in the occurrence of “cardiac shock”. Methods A total of 36 Sprague Dawley (SD) rats were randomly divided into sham scald group and 30% TBSA full-thickness scald injury group. The 4.8 kb deletion of mtDNA, the contents of ATP, ADP, and AMP in mitochondria, and Tn I in serum were determined at 1, 3, 6, 12, and 24 h after burn. Results ① Partial or full 4.8-kb deletion of mitochondrial DNA (mtDNA) was found in some rats at 1, 3, and 24 h after scald. ② Level of ATP in myocardial mithochondia decreased obviously at 1, 3, 6, and 24 h after severe burn (P<0.05 or P<0.01). ③ The content of Tn I in serum was elevated dramatically at 1 h after burn and peaked at 6 h. The changes were significant (P<0.05 or P<0.01). Conclusion The 4.8 kb deletion of mtDNA may induce the disturbance of energy metabolism in rat myocardial mitochondria at the early stage of severe burn, which may accelerate the occurrence of “cardiac shock”.