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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。
Objective To observe the improvement of myocardial injury induced by a large area escharectomy in early postburn burn rats and to explore its molecular mechanism. Methods Sixty-six SD rats were randomly divided into non-escharectomy group (30), escharectomy group (30) and normal control group (6). The first two groups of rats were inflicted with 30% TBSA degree scald (hereinafter referred to as burns, escharectomy 20 min after excision of all eschar tissue) and 1, 3, 6, 12, 24 h after injury 6) were used to detect ATP content, TnI and deletion of 4.8 kb fragment of myocardial mitochondrial DNA in mitochondria. Normal control rats without treatment, the same detection of the above indicators. Results (1) The content of ATP in myocardial mitochondria decreased in both groups, but the values of 1, 6b escharectomy group were (0.90 ± 0.27) and (0.66 ± 0.19 ) μg / mg protein, which was significantly (P <0.05) higher than that of the non-escharectomy group (0.74 ± 0.18) and (0.46 ± 0.21) μg / mg protein. (2) Compared with the normal control group, the content of TnI in sera of rats in escharectomy group did not change obviously at 1, 3 hours after injury, but the difference was statistically significant at 1, 3 and 6 hours after injury .05 or 0.01). (3) In the non-escharectomy rats, some or all large fragments of mtDNA 4.8kb were found at 1, 3 and 24 hours after injury. Rats in escharectomy group were only deleted 1h and 12h after injury, and the average deletion rate Lower than non-escharectomy group. Conclusion A large area of escharectomy can significantly reduce the degree of myocardial injury after burn injury, and its mechanism may be related to the reduction of mtDNA deletion rate in early posttraumatic myocardium.