MENG Tao, YANG Mo, GAO Ye, DUAN Hua-wei, DAI Yu-fei, ZHENG Yu-xin. Cardiovascular damage in mice induced by inhalation of carbon black aerosols[J]. Journal of Environmental and Occupational Medicine, 2018, 35(8): 709-715. DOI: 10.13213/j.cnki.jeom.2018.18246
Citation: MENG Tao, YANG Mo, GAO Ye, DUAN Hua-wei, DAI Yu-fei, ZHENG Yu-xin. Cardiovascular damage in mice induced by inhalation of carbon black aerosols[J]. Journal of Environmental and Occupational Medicine, 2018, 35(8): 709-715. DOI: 10.13213/j.cnki.jeom.2018.18246

Cardiovascular damage in mice induced by inhalation of carbon black aerosols

  • Objective To explore the injury of cardiovascular system and its potential mechanism in mice induced by repeated inhalation of nanoscaled carbon black (CB) aerosols.

    Methods Eight-week-old male C57BL/6 mice were divided into control group (n=24), exposure group (n=12), and recovery group (n=12). The exposure mice were exposed to CB aerosols in an inhalation chamber at 30.16 mg/m3 for 6 h/d for a continuous inhalation of 28d; the recovery mice were exposed to CB aerosols for 28 d and then recovered for another 28 d; the control mice were exposed to filtered air. The concentration and aerodynamic diameter of CB particles were daily monitored during the exposure. Nine mice in each group were randomly selected and the cardiac function parameters were determined using electrocardiography (ECG) under anesthesia at 24 h after the last exposure or recovery. The serum samples were collected for the determination of myocardial enzymesincluding creatine kinase (CK), creatine kinase isoenzyme (CK-MB), lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) and inflammatory cytokinesincluding interleukin-1β (IL-1β), interleukin-6(IL-6), interleukin-8(IL-8), and tumor necrosis factor-α (TNF-α). Heart tissue samples were collected for the detection of inflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) and oxidative stress indicessuch as superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA). The histopathological evaluation on heart tissues of three mice in each group was conducted after HE staining.

    Results The average concentration of CB particles was (30.16±3.52) mg/m3, the particles with aerodynamic diameter less than 400 nm accounted for 82.53%, and the particles with aerodynamic diameter less than 800 nm accounted for 98.13%. On exposure day 7, 14, 21, 28 and during the recovery, there was no difference in body weight between the exposure mice and the control mice. Compared with the control group, S-T segment and PR interval of ECG in the exposure group and the recovery group increased significantly (P < 0.05), but no difference was observed in other ECG indices (P > 0.05). The activities of CK and CK-MB in serum of mice in the exposure group were 1.42 and 1.24 times as high as those of the control group (P < 0.05), and the two indicators of mice in the recovery group decreased to normal levels. The serum levels of IL-6, IL-8, and TNF-α in the exposure group were 1.79, 1.89, and 1.70 times as high as those of the control group (P < 0.05), and only the IL-6 level in heart tissues was 1.40 times higher. Although the serum levels of IL-6 and IL-8 had slight reductions in the recovery period, their levels were still higher than those in the control group (P < 0.05), and there was no difference in the levels of IL-1β, IL-6, IL-8, and TNF-α in heart tissues between the control group and the recovery group. SOD activity decreased and MDA level increased in heart tissues of mice after CB inhalation (P < 0.05), and no differences were observed in the two indicators between the recovery group and the control group. Histopathological examination results showed that myocardial fibers were well arranged in the control group; CB particles were not observed in heart tissues of mice after CB inhalation, but myocardial fibers were disarranged, and myocardial cell edema and inflammatory cells were observed; in the recovery group, a small amount of inflammatory cells were also seen in the heart tissue samples of mice.

    Conclusion Ischemic injury in heart of mice is induced following repeated inhalation of 30.16 mg/m3 CB nanoscaled aerosols, and the mechanism might be related to inflammatory injury and oxidative stress induced by CB particles.

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