Objective To investigate the pulmonary injury induced by novel nano materials, nitrogen-doped nano titanium dioxide (N-nTiO2).
Methods Forty-two specific-pathogen-free SD rats were divided into one blank control group and five N-nTiO2 groups (13.64, 27.27, 40.91, 54.55, and 68.18 mg/kg, respectively, in terms of body weight thereafter), with seven rats in each group. The rats were exposed to N-nTiO2 by intratracheal instillation every three days and for 28 days. Lung function changes were monitored with lung function measurement instrument, the quantity of total protein and activities of lactate dehydrogenase and alkaline phosphatase in bronchoalveolar lavage fluid were measured with multi-mode enzyme-labelled meter, and the lung histopathological damage was observed using HE staining.
Results The body weight gain was less in each N-nTiO2 group compared with the blank control group (P < 0.05). The minute ventilation volume significantly increased in the 54.55 and 68.18 mg/kg N-nTiO2 groups compared with the blank control group (P < 0.05), the peak expiratory flow significantly increased in the 40.91 mg/kg and above N-nTiO2 groups (P < 0.05), and the tidal volume and peak expiratory flow significantly increased in the 68.18 mg/kg N-nTiO2 group (P < 0.05). Compared with the blank control group, the quantity of total protein significantly increased only in the 40.91 mg/kg N-nTiO2 group (P < 0.05), the enzyme activity of lactate dehydrogenase increased in the 27.27 mg/kg and above N-nTiO2 groups, and the enzyme activity of alkaline phosphatase increased in the 54.55 mg/kg and above N-nTiO2 groups (P < 0.05). The results of lung histopathological examination results demonstrated that lung tissue injury was aggravated in the groups treated with higher levels of N-nTiO2, such as cell proliferation, hypermia, and inflammatory cell infiltration, as well as lung obstruction, atelectasis, and consolidation.
Conclusion Intratracheal instillation of N-nTiO2 may induce not only organic lesion but also lung function impairment in rats.
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