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目的观察维生素C对纳米二氧化钛染毒小鼠心脏损伤的保护作用。方法昆明小鼠ig给予维生素C 100,200和400 mg·kg-12 d,后3 d间隔4 h后ig给予纳米二氧化钛2 g·kg-1,末次染毒后24 h进行指标检测。生理记录仪测定心电图;生化法测定血清中心肌酶活性及血清和心肌组织超氧化物岐化酶(SOD)和谷胱苷肽过氧化酶(GSH-Px)活性;彗星实验检查心肌单细胞DNA损伤;HE染色光镜观察心脏组织病理改变。结果纳米二氧化钛2 g·kg-1染毒小鼠后,心电图检查发现ST段抬高、T波高尖,与正常对照组比差异有显著性(P<0.05);染毒组血清中心肌酶活性均较正常对照组明显升高(P<0.05),血清和心肌组织中SOD和GSH-Px活性降低(P<0.05)。彗星实验结果表明,纳米二氧化钛2 g·kg-1染毒组彗星Olive尾距(OTM)显著高于正常对照组(P<0.05)。组织病理学结果显示,纳米二氧化钛2 g·kg-1染毒后小鼠心肌组织出现细胞水肿、心肌纤维紊乱、炎性细胞增多。给予维生素C 100,200和400 mg·kg-1处理后,抬高的ST段降低,OTM值下降,心肌酶的活性降低,与纳米二氧化钛染毒组相比有显著性差异(P<0.05);病理组织学检查结果显示,心肌水肿减轻,炎性细胞减少,并增加心肌组织中的SOD和GSH-Px活性,与纳米二氧化钛处理组相比,差异有显著性(P<0.05)。结论纳米二氧化钛可造成小鼠心肌损伤,维生素C可对抗纳米二氧化钛所致的心脏损伤,其机制可能与其增强心肌组织的抗氧化能力有关。
Objective To observe the protective effect of vitamin C on cardiac injury induced by nano-TiO2 in mice. Methods Kunming mice were given vitamin C 100, 200 and 400 mg · kg-12 d ig after ig for 4 h, and then were given ig 2 g · kg-1 nano-titanium dioxide for 4 h after the last dose. The electrocardiogram was used to measure the activity of serum myocardial enzymes and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in serum and myocardium. The DNA damage of myocardial cells was detected by comet assay The pathological changes of heart tissue were observed by HE staining. Results After intravenous administration of 2 g · kg-1 nano-TiO2, ST-segment elevation and T-wave tip were found on electrocardiogram (P <0.05). Serum myocardial enzyme activities Compared with normal control group, the activity of SOD and GSH-Px in serum and myocardium decreased significantly (P <0.05). The results of comet assay showed that the OTM of Comets in the 2 μg · kg -1 Nano-TiO 2 group was significantly higher than that of the normal control group (P <0.05). Histopathological results showed that the myocardial tissue of mice with 2 g · kg-1 nano-titania showed cell edema, myocardial fibrosis and inflammatory cells increased. After treatment with 100, 200 and 400 mg · kg-1 of vitamin C, the elevated ST segment decreased, the OTM value decreased and the activity of myocardial enzyme decreased, which was significantly different from that of nano-TiO2 (P <0.05) Histological examination showed that myocardial edema, inflammatory cells decreased and SOD and GSH-Px activities in myocardium were increased. There was a significant difference between the two groups (P <0.05). Conclusion Nano-titanium dioxide can cause myocardial damage in mice, and vitamin C can counteract the cardiac damage caused by nano-titania. The mechanism may be related to the anti-oxidation ability of myocardial tissue.