牛磺酸对烫伤大鼠心肌线粒体成分和酶活性的保护作用

Protective effects of taurine on myocardial mitochondria and their enzyme activities in rats with severe bum

目的了解牛磺酸对大鼠烫伤后心肌线粒体成分和酶活性变化的影响。方法将120只大鼠背部脱毛后造成30％TBSA的Ⅲ度烫伤。分为烫伤组（60只），伤后腹腔注射等渗盐水（4mL·kg^-1·1％TBSA^-1）；牛磺酸治疗组（60只），伤后腹腔注射20g/L牛磺酸液（200mg／kg）。伤后1、3、6、12、24、48h处死大鼠，取心肌组织检测心肌线粒体琥珀酸脱氢酶（SDH）、细胞色素c氧化酶（CCO）、超氧化物歧化酶（SOD）、ca^2＋一腺苷三磷酸酶（ATPase）活性和细胞色素c、细胞色素aa3、丙二醛（MDA）、细胞质及线粒体内ca^2＋含量。另取10只大鼠作为对照组，模拟烫伤不予补液，1h后处死大鼠取心肌组织检测以上指标。结果烫伤组大鼠伤后1h CCO活性即开始下降，伤后6、12h下降最明显，而SDH活性在伤后6h下降最明显，且各时相点均低于对照组；牛磺酸治疗组CCO和SDH下降不明显，伤后3、6、12hCCO活性与烫伤组比较，差异有统计学意义（P〈0．05）。伤后3、6、12、及24h烫伤组心肌线粒体细胞色素c和细胞色素aa3均显著降低，而牛磺酸组虽然有所下降，但以上4个时相点的值均高于烫伤组（P〈0．05）。烫伤组SOD活性在伤后3、6、12h均显著性下降，Ca^2-ATPase活性在伤后3、6、12及24h均有不同程度下降；而牛磺酸治疗组虽然有所下降，但以上4个时相点SOD、Ca^2-ATPase值均高于烫伤组（P〈0．05）。伤后3～48h烫伤组、牛磺酸治疗组MDA值均高于对照组（P〈0．05），但牛磺酸治疗组低于烫伤组（P〈0．05）。伤后1h烫伤组大鼠心肌线粒体中Ca^2即开始升高为13．7±1．5，伤后3、6、12、24h分别为24．8±2．6、29．7±3．1、16．3±1．9及13．5±1．7，均高于对照组（10．7±1．6，P〈0．05）；心肌细胞质中ca“在伤后3、6、12、24h也明显高于对照组（P〈0．05）。伤后3、6、12及24h牛磺酸治疗组大鼠心肌线粒体中ca“浓度分别为16．8±2．8、18．7±1．9、10．5±1．8及13．3±1．7，均低于烫伤组。结论牛磺酸对烫伤大鼠心肌线粒体成分和酶活性破坏具有保护作用，其机制与提高线粒体清除氧自由基的能力和减轻Ca^2＋超载有关。

Objective To investigate the effects of taurine on myocardial mitochondria and their enzyme activities in rats with severe burn. Methods One hundred and twenty healthy adult Wistar rats were subjected to 30% TBSA full-thickness burn. They were randomly divided into burn group （ B, with intraperitoneal injection of isotonic saline） , treatment group （ T, with intraperitoneal injection of taurine, 200 mg/ kg） ,with 60 rats in each group . Ten rats with sham scald were used as control（S group）. The myocardial tissue samples in B and T groups were harvested at 1, 3, 6, 12, 24 and 48 postburn hours（PBH） for determintion of activity respectively of succinate dehydrogenase （SDH） , cytochrame oxidase （CCO） , the superoxide dismutase （SOD）, Ca^2＋ -ATPase in mitochondria, and contents of cytochrome c （Cyt c）, cytochrome aa3 （Cyt aa3） , malondlaldehyde（MDA） ,and Ca^2＋ in mitochondria and cytoplasm . The myocardial tissue samples of controls were harvested at 1 PBH for determintion of above indices. Results The activity of CCO in B group was decreased at 1 PBH , especially at 6 , 12 PBH. The activity of SDH in B group was decreased to lowest level at 6 PBH , and its value was lower than that of S group at each time point . The activity of CCO or SDH in T group was not obviously decreased, and the activity of CCO at 3,6,12 PBH showed significant difference compared with B group （ P 〈0.05）. The contents of Cyt aa3 and Cyt c in B group at 3,6, 12,24PBH were obviously decreased, which were significantly lower than those in T group （ P 〈 0.05 ）. The activity of SOD in B group at 3, 6, 12 PBH was obviously decreased, the activity of Ca^2＋ -ATPase at 3, 6, 12 and 24 PBH was decreased to different extent, which was significantly lower than those in T group （ P 〈 0.05 ）. The MDA contents in B and T groups were higher than that in S group at 3 ～ 48 PBH , and it was highest in B group （ P 〈 0.05）. The Ca^2＋ content of mitochondria in B group at 1 PBH was increased （13.7 ±1.5） ,and it was （24.8±2.6）, （29.7±3.1）, （16.3±1.9） and （13.5±1.7） at 3, 6, 12, 24 PBH respectively, and they were all higher than that of S group （ 10. 7 ± 1.6, P 〈 0.05 ）. The Ca^2＋ contents of cytoplasm in group B at3-24 PBH were also higher than that in S group （ P 〈0.05）. The Ca^2＋ content of mitochondria in T group at 3 ,6 ,12 ,24 PBHwas （16.8±2.8）, （18.7±1.9）, （10.5±1.8） and （13.3±1.7）respectively,which were lower than that in B group at every time point. Conclusion Taurine have protective effect on mitochondria and their enzyme activities in myocardium in rats with severe burn,and it may be attributable to improvimg the ability of eradicating oxygen free radicals and alleviating Ca^2＋ overload in the mitochondria.