Effects Of Ulinastatin Therapy On Acute Lung Injure After Seawater-Driwing In Rats

Background:Seawater drowning induced acute lung injury （SD-ALI） is the majorcause of death in drowning mariners. The main pathophysiologiccharacteristics of SD-ALI are hypoxemia,hypercapnia and metabolicacidosis. At present,the pathogenesis of SD-ALI was thought to bethe direct damage of lung by seawater and inflammatory overreactionof body after seawater drowning. Polymorphonuclear neutrophil （ PMN）and cytokines play important roles in the pathogenesis of SD-ALI.Many clinical and experimental researches have revealed thatulinastatin had therapeutic effect on non cardiogenic pulmonaryedema. The mechanism of the therapy might be inhibition of PMNcollection and activation in inflammation areas, and release ofcytokines. In this study,a rat SD-ALI model was made, and level changeof PMN and cytokines was analyzed. Pathogenesis of SD-ALI wasdiscussed. The therapeutic effect and mechanism were discussedthrough observation of level change of myeloperoxidase （MPO） activation in rat lung and cytokines in bronchoalveolar lavagefluid（BALF） after treatment by ulinastatin.Objective：1.To make a rat SD-ALI model.2.To observe the change of cytokine levels in BALF and activationof MPO in rat lung in SD-ALI rat, and to investigate the pathogenesisof SD-ALI.3.To investigate the therapeutic effect of ulinastatin on SD-ALIand the mechanism of it.Methods：1.Modeling of rat SD-ALI.Twenty two male SD rats were chosen asexperimental subjects. Respiratory rate（RR） and arterial partialpressure of oxygen（PaO₂） were examined. Seawater was injected （4ml/kg）constantly through rat tracheal in 3 min. The change of RR wasobserved and PaO₂ was tested 30min and 60min after seawater perfusion.The rats were killed 60min after seawater perfusion, and pathologicalchange of lung tissue was observed.2.Thirty male SD rats were randomly divided into three groups intens：a control group,a model group,and an Ulinastatin treatmentgroup. The model group and treatment group received artificialseawater（4 mL/kg）by intratracheally instillation. The Ulinastatintreatment group received Ulinastatin（100000 U/kg）after infusingseawater. The model group only received an injection of same amountof saline. PaO₂ was tested at 0h, 0.5h and 4h. Rats in each group weresacrificed at 4h. The pathological changes of lungs were evaluatedby hematoxylin-eosin stain. Lung/body weight ratios were reckoned to assess the level of pulmonary edema. Concentrations of tumornecrosis factor（TNF）-α,interleukin（IL）-1β,IL-6 and IL-10 inbronchoalveolar lavage fluid（BALF）were detected by enzyme-linkedimmunosorbent assay（ELISA）. The myeloperoxidase activity in lungtissue homogenates were measured by colorimetric method.Results：1.After seawater drowning, RR increased, cyanosis appeared inmouth and nose, coarse rales was spread all over in both sides oflungs. PaO₂ and oxygenation index were decreased dramatically 30minand 60min after drowning. Change of PaO₂ and oxygenation index in bothtime points and the pathological changes meet the standard ofdiagnosis acute lung injury（ALI）.2.PaO₂ of rat decreased sharply at 0.5h after drowning. At 4h, PaO₂in treatment group increased significantly（p＜0.05）. In model groupand treatment group, TNF-α，IL-1β, IL-6 and IL-10 in BLAF, lungtissue MPO activity, and W/D were all significantly higher than incontrol group（p＜0.05）. In model group, alveolar wall was broken,and pulmonary interstitial edema was observed. There were alsohemorrhage and edema in alveolar, and microthrombus was formed. Thelung showed partially atelectasis, compensating emphysema andinflammatory cell infiltration. In treatment group, the pathologicalchanges were significantly attenuated（p＜0.05）.Conclusions：1.SD-ALI rat model can be made successfully through seawaterinjection （4ml/kg） constantly through rat tracheal in 3 min.2.Both of direct damage by seawater and inflammatory overreaction of body is one of the major pathogenicfactors of SD-ALI.3.Ulinastatin attenuates SW-induced ALI,which may be related toits inhibitory effects on inflammation reaction by regulatingcytokine secretion and inhibition of inflammatory cell collectionand activation.