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. 2020 May 8;2020:4260204. doi: 10.1155/2020/4260204

Figure 1.

Figure 1

Experimental protocol. SD rats were divided into control, PM2.5, COPD, and PM2.5+COPD groups. During weeks 0~8, for the COPD and PM2.5+COPD groups, the COPD rat model was prepared by using repeated cigarette smoke inhalation and bacterial infection. During weeks 8~16, rats in the PM2.5 and PM2.5+COPD groups were exposed to concentrated PM2.5 atmosphere in the whole-body exposure chamber, 4 hours per day. Rats in the control group were exposed to filtered air all the time. At weeks 0, 4, 8, 12, and 16, the noninvasive lung function (TV, PEF, and EF50) were measured. All rats were sacrificed within 24 h of the last PM2.5 exposure. And lung function, pulmonary histopathology, inflammatory cytokines, oxidative stress, mucus secretion, and proteinases/antiproteinases were detected. Control: healthy rats; PM2.5: particulate matter 2.5 treatment alone rats; COPD: chronic obstructive pulmonary disease rats; PM2.5+COPD: COPD rats exposed to prolonged PM2.5 for 8 weeks. TV: tidal volume; PEF: peak expiratory flow; EF50: expiratory flow 50%.