大鼠双下肢骨折合并失血对心肌细胞损伤的作用及其机制

目的：探讨双下肢骨折创伤失血反应可否诱导心肌细胞发生凋亡反应，为深入研究骨折创伤后心肌损伤机制奠定基础。方法：SD大鼠20只，随机分为对照组及创伤组（n=10），制备双下肢骨折创伤失血模型；原代心肌细胞培养复制创伤模型。ELISA检测血清IL-2、IL-6、IL-10、TNF-α水平；心肌组织HE染色、Tunel试验观察心肌受损、凋亡；Western blot及RT-PCR检测心肌组织凋亡调控基因Bcl-2/Bax表达变化。结果：创伤后血清炎性因子时间依赖性改变，IL-2（8 h）、IL-6、IL-10（4 h）、TNF-α（1 h）达到峰值，随后逐步回落；心肌HE染色发现心肌细胞肿大，排列紊乱，炎细胞浸润；Tunel试验证实大量核染成棕褐色的心肌细胞，凋亡指数增加（P<0.05）；Western blot及RT-PCR检测表明，无论在体及心肌细胞培养中，促凋亡基因Bax表达上调（P<0.05），而抑凋亡基因Bcl-2表达下调（P<0.05）。结论：大鼠双下肢骨折创伤失血反应通过诱导心肌细胞凋亡进而造成心肌损伤。

Effect of fracture of lower limbs with hemorrhage on myocardial injury and its mechanism in rats

Objective:To test whether myocardial apoptosis can be induced by traumatic fracture of lower limbs with hemorrhage, in order to lay a foundation of myocardial injury after traumatic fracture for the follow-up study. Methods:Twenty SD rats were randomly divided into two groups, i. e. control group and trauma group(n=10). A rat model of traumatic hemorrhage was establish, and a traumatic model of the original generation of myocardial cell culture was constructed in vitro. The level of interleukin-2(IL-2),IL-6,IL-10 and tumor necrosis factor-α(TNF-α) in rat serum was detected by ELISA at 0, 1, 2, 4, 8, 12, 16, 24 and 48 hour to find the most significant point. The pathological cardiac injury in rats was observed by HE staining under a microscope, and the apoptosis of cultured cardiomyocyte in vitro was detected by TUNEL methods. The expressions of apoptosis gene,(Bcl-2) and Bax, in myocardium of rat and cultured cardiomyocyte in vitro were detected by Western blot and RT-PCR. Results:At the 4^th hour after trauma, IL-6 and IL-10 in the serum of rats reached its highest, IL-2 reached its lowest at the 8th hour after trauma, and TNF-αreached its highest at 1 hour after trauma, then all recovered to their normol level gradually. Myocardial HE staining indicated that cardiomyocyte was swelling, disordered derangement, inflammatory cell infiltrated; a large number of myocardial cell nuclei was dyedbrown in TUNEL test which proved that the apoptosis index increased (P<0.05). Western blot and RT-PCR results showed that the expression of pro-apoptotic gene Bax was up-regulated (P<0. 05), while expression of anti apoptosis gene Bcl-2 down-regulated (P<0.05). Conclusion:The myocardial apoptosis can be induced by traumatic fracture of lower limbs with hemorrhage in rats, and then lead to myocardial injury.