烧伤后早期一次大面积切痂改善大鼠心肌损伤机制的研究

目的观察烧伤后早期一次大面积切痂对大鼠心肌损伤的改善状况,并探讨其分子机制。方法将66只SD大鼠随机分为非切痂组(30只)、切痂组(30只)与正常对照组(6只)。将前两组大鼠造成30%TBSAⅢ度烫伤(以下称烧伤,切痂组伤后20 min切除全部焦痂组织),并于伤后1、3、6、12、24 h(每时相点6只)检测大鼠心肌线粒体中腺苷三磷酸(ATP)含量、血清中肌钙蛋白Ⅰ(TnI)含量以及心肌线粒体DNA(mtDNA)4．8 kb大片段缺失情况。正常对照组大鼠不作处理,同样检测上述指标。结果(1)两致伤组大鼠心肌线粒体中ATP含量均有下降,但伤后1、6b切痂组该值分别为(0．90±0．27)、(0．66±0．19)μg/mg蛋白,较非切痂组的(0．74±0．18)、(0．46±0．21)μg/mg蛋白有显著改善(P＜0．05)。(2)与正常对照组比较,切痂组大鼠伤后1、3h血清中TnI含量变化不明显,但伤后1、3、6h与非切痂组比较差异有统计学意义(P＜0．05或0．01)。(3)非切痂组大鼠在伤后1、3、24h发生了mtDNA 4．8kb的部分或全部大片段缺失,切痂组大鼠仅在伤后1、12h发生缺失,且平均缺失率较非切痂组低。结论烧伤后早期一次大面积切痂能显著减轻伤后心肌受损程度,其机制可能与降低伤后早期心肌mtDNA缺失率有关。

Study on the mechanism of alleviation of myocadial injury after early escharectomy en masse of severe burns in rat

OBJECTIVE: To investigate the alleviation of myocadial injury of rats after early escharectomy en masse of severe burns, and to explore its molecular mechanism. METHODS: Totally 66 SD rats were randomly divided into normal control (n=6), non-escharectomy (NE, n=30) and escharectomy (E, n=30, with total escharectomy 20 minutes after burns ) groups. The rats in the NE and E groups were inflicted with 30% TBSA full-thickness scald. The content of ATP in mitochondria, troponin I (Tn I) in serum and 4.8-kb deletion of myocardial mitochondrial DNA (mtDNA) of the rats in each group were determined at 1, 3, 6, 12 and 24 post-scald hours (PSH). RESULTS: (1) The content of ATP in myocardial mitochondria was decreased in both E and NE groups, but it was obviously increased at 1 and 6 PSH (0.90 +/- 0.27 microg/mg 0.66 +/- 0.19 microg/mg) in E group when compared with those in NE group (0.74 +/- 0.18 microg/mg, 0.46 +/- 0.21 microg/mg, P < 0.05). (2) There was no obvious change in the serum content of Tn I in E group at 1 and 3 PSH, but the respective content in 1, 3 and 6 PSH was markedly lower than those in NE group (P < 0.05). (3) The 4.8 kb deletion of myocardial mtDNA was found at 1, 3, 24 PSH in NE group, while it was observed only at 1, 12 PSH in E group. The partial and whole deletion rate in E group was lower than that in NE group. CONCLUSION: Early escharectomy en masse can significantly alleviate the myocardial injury after burns,which might be related to its effect in lowering the deletion rate of myocardial mtDNA at early postburn stage.