Effects of acidification pretreatment for respiratory acidosis on the expression of matrix metalloproteinase-9 in rat lung tissues following ischemia/reperfusion

To establish rat model of lung ischemia/reperfusion (IR) in vivo, and to explore the effects of acidification pretreatment for respiratory acidosis on the expression of matrix metalloproteinase-9 (MMP-9) and the possible mechanisms. Methods: A total of 36 male Sprague-Dawley rats were divided into a sham group (S group), a IR group, and an experiment group (RA group) (n=12 in each group). The rat left lung hilum in the S group was dissociated, followed by perfusion without ischemia. After the left lung hilum in the IR group was blocked for 45 min, the rats were followed by reperfusion for 180 min. After left lung hilum in the RA group was dissociated, the respiratory parameters were adjusted so that pressure of end tidal carbon dioxide (PETCO2) reached 56-65 mmHg (1 mmHg=0.133 kPa) for 5 min, then the rats was subjected to IR. Lung tissue wet/dry (W/D) and lung permeability index (LPI) were calculated, while the lung histopathology was observed and the MMP-9 protein expression were measured. Results: Compar