The Expression Of MUC5AC Protein With Mechanical Ventilator-induced Lung Injury In Rats

Objective This paper has two direction of research.One is target for investigating the expression of MUC5AC protein,MUC5ACmRNA,Bronchoalveolar lavage fluid?BALF?tumor necrosis factor?TNF?-?,interleukin?IL?-1?and IL-6 following ventilator-induced lung injury in rats.The second one is focus on discussing the role of Muc5ac in ventilator-induced lung injury,which provide a theoretical foundation and methodology for prevention and deduce ventilator-induced lung injury in clinical.Methods Thirty-six healthy male Sprague-Dawley?SD?rats,weighing 250³00g,6-8weeks old were split into three groups?n=12 each?by random number table,including control group?C?,low tidal volume group?L?and high tidal volume group?H?.All SD rats fasted for 12 hours before experiment and free access to water.Animals were anesthetized intraperitoneally with 2%sodium pentobarbital 80mg/kg,same time,polyethylene catheter was inserted into the left carotid artery for direct blood pressure monitoring and heart rate.Right external jugular vein catheter for intravenous vecuronium pump to relax muscle,and a tracheostomy was established using a 14-gauge plastic canula.Animals were ventilated?small animal ventilator?with room air via machine.Group C keep spontaneous breathing,the rest with Group L and Group H.Group L:tidal volume 6ml/kg.Group H:tidal volume 20ml/kg.Group L and Group H are under mechanical ventilation,with Respiratory 80 frequency per minute,keep breathing in and out ratio 1:1,21%of inhaled oxygen concentration and 0 of positive end-expiratory pressure.After mechanical ventilation,blood gas analysis was calculated by PaO2,while animals were sacrificed by exsanguination.For BALF using in determining expression of inflammation,the left lungs were lavaged three times with2.5ml of ice-cold lavage buffer;the remaining cell pellet was resuspended in 1ml of phosphate-buffered saline for neutrophil count.The expression of TNF-?,IL-1?and IL-6 were detected in BALF by ELISA.The upper lobe of the right lung was fixed with 4%paraformaldehyde And processed it into paraffin-embedded sections,then go for HE staining.Morphological changes were observed under light microscope.Lung wet-to-dry weight ratio was used as an index of pulmonary edema formation.The wet right middle lungs were weighed and then placed in an oven for 24h at 80?and weighed when they were dry.The remaining right lung tissue was frozen at-80°C and used for the determination of mucin MUC5AC and MUC5AC mRNA.The expression of MUC5AC were detected by ELISAand immunohistochemistry.The expression of MUC5ACmRNA were detected by fluorescent quantitative real time reverse transcriptase polymerase chain reaction.Results Compared with group C,the lung tissue structure of group L was still clear,a small amount of alveolar wall was thickening,a small amount of alveolar hemorrhage,edema,alveolar septum are basically normal,a small amount of goblet cells appear between epithelial cells.For H group,the lung tissue structure is destructed,alveolar septum are thickening,a large number of red blood cells appear in the alveolar cavity,a large number of inflammatory cells gathered,a large number of goblet cells appear metaplasia,some of the wall cells almost are goblet cells.bronchoalveolar secretion was significantly increased.The neutrophil counts and the W/D were significantly increased in group H?P<0.01?,the expression of TNF-?,IL-1?and IL-6 in BALF and the expression of MUC5AC and MUC5ACmRNA were significantly increased in group L and in group H?P<0.05 or P<0.01?,PaO₂ were significantly decrease in group H?P<0.01?,The neutrophil counts,the W/D and PaO₂ have no significantly increased or decreased in group L;Compared with group L,the neutrophil counts,the W/D,the expression of TNF-?,IL-1?and IL-6 in BALF and the expression of MUC5AC and MUC5ACmRNA were significantly increased in group H?P<0.01?,PaO₂was significantly decrease in and group H?P<0.01?.Conclusion 1.Lung injury in rats caused by mechanical ventilator increased lung tissue lesions,neutrophil infiltration Whiledestroying the oxygenation function of the lung.2.Mechanical ventilator-induced lung injury in rats elevate the levels of inflammatory cytokines,and promote the expression of MUC5AC protein and MUC5ACmRNA.