The Treatment Of Aprotinin In PFIB-induced Acute Lung Injury In Rats

Objective To investigate the treatment of Aprotinin on acute lung injury induced byperfluoroisobutylene(PFIB) in rats. Methods According to body weight,forty adultmale Sprague-Dawley rats were randomly divided into ALI group(I group),aprotiningroup(5mg/kg,15mg/kg,30mg/kg,L/M/H group) and saline control group(N group).The rats in first four groups were exposed to a sublethal concentration of PFIB (287mg/m3) for5minutes in a flow-past whole-body chamber1.Toxic gas concentration ofPFIB was analyzed by gas chromatography apparatus.The rats in aprotinin group wereintravenously injected with different dose of aprotinin (5mg/kg,15mg/k,30mg/kg) thirtyminutes after PFIB were inhalated. Observed the breath, diets,mentation and activitiesin each group of rats.Ended the experiment after24hours later. Weighed prior tosacrifice.Rats were anesthetized by intraperitoneal injection of chloral hydrate(0.4ml/100g).Then,opened the abdominal cavity and extracted2ml blood fromabdominal aortic venous for detecting the levels of TNF-ɑ andinterleukin-6inserum.Measured the total protein content in bronchoalveolar lavage fluid (BALF) afterthe left lung was lavaged with5ml normal saline.The middle lung tissue was taken tocalculate wet-to-dry weight (W/D) ratio. The upper right lung and down right lung wereprepared to homogenates for measuring the content of neutrophil elastase(NE)anddisplaying the expression of NF-kB by Western blot.Taken the middle-right lung for HEstaining after it was fixed by10%formalin and embedded by paraffin.Observed thepathological changes of lung tissue in the light microscope.Results The generalperformance of rats in each group:Before exposure to PFIB,the breath and activities ineach group were steady and normal.The animals in I group showed rapid breathing,restlessness, cyanosis,then followed by asthma, nose and mouth appeared liquid or foam, fur spear and weight loss after the exposure. Certainly,the activities were obviouslydecreased. The situations in group L, M and H were more improved than that in the Igroup.The H group was most.2.The wet-to-dry weight ratio(W/D): The wet-to-dryweight ratio in group I, L, M and H was significantly higher than that in group N (P <0.05).The wet-to-dry weight ratio in group L was not lower compared to group I(P>0.05),.While,it was lower in group M and H.The ratio in group H was most significantlyreduced(P <0.05).3.The total protein content in bronchoalveolar lavage fluid (BALF):The total protein content in bronchoalveolar lavage fluid of group I,L,M and H wassignificantly higher than N group (P <0.05).But,the content in group L was not lowerthan group I(P>0.05).In group M and H,the total protein content in bronchoalveolarlavage fluid were lower compared to group I(P <0.05).The results in group H weremost significantly reduced(P <0.05).4.The levels of TNF--α in serum:The levels ofTNF--α in serum of group I,L,M and H were significantly higher than N group (P <0.05).In group M and H,the levels of TNF--α were lower compared to group I(P <0.05)The values in group H were most significantly decrease(P <0.05).5.The levels ofIL-6in serum:The levels of IL-6in serum of group I,L,M and H were significantlyhigher than N group (P <0.05).In group M and H,the levels of IL-6were lowercompared to group I(P <0.05).The values in group H were most significantly reduced(P<0.05).6.The content of neutrophil elastase in lung homogenate:The content ofneutrophil elastase in lung homogenate of group I,L,M and H was significantly higherthan N group (P <0.05).In group M and H,the contents of neutrophil elastase werelower compared to group I(P <0.05).The values in group H were most significantlyreduced(P <0.05).7.The expression of NF-kB by Western blot in lung homogenate:Theexpression of NF-kB by western blot in group I, L, M and H was significantly higherthan that in group N.The expression was lower in group H compared to group I, L andM.8.The appearance of lung tissue in naked eyes:In group N,the lung tissue surfacewere smooth,whole,pink,no congestion, no bleeding, no edema, no infarction and noliquid overflow.In group I,the lungs were dark red, larger volume,hypoelasticity,congestion,edema and pink foamy liquid could be seen when cut the lung.The injuries in group were like the group I.The situation in group M and H were better than group I.9.The pathological changes of lung tissue in the light microscope:There was no injuriesin group N with alveolar structural integrity,alveolar space clarity,alveolar septa withoutedema, inflammation and any other changes.The damage in group I was most obviouswith lung epithelial cell injury,alveolar wall thickening,interstitial lung widened, edema,exudation.8inflammatory cell infiltration, diffuse telangiectasia,alveolar hemorrhage,pulmonary interval break,transparent film formation of alveolar collapse.The extent ofdamage was also heavier in L group.The extent of damage was lighter in group M andH,and the H group was the lightest injury. Conclusion1.In this topic, the experimentsuccessfully build the animal model of acute lung injury after the rats are exposed to theperfluoroisobutylene (PFIB) in a flow-past whole-body chamber.2.High dose ofaprotinin can obviously reduce the pulmonary inflammatory reaction after exposure toPFIB in rats. It is also can reduce the exudation of protein and relieve edema in thelung.But the effect of low and middle dose of aprotinin is not obvious.The mechanismof aprotinin which can reduce acute lung injury may be connected with lowering theactivity of neutrophil elastase, inhibiting excessive inflammation,reducing the release ofTNF-α, IL-6and suppressing the expression of NF-kB.