| Objective:1.Innovative modeling method: the rat model of seawater submersion lung injury was constructed by intubation through breath tube;2.Explain the pathogenesis of seawater submersion induced lung injury;3.To observe and compare the protective effect of ambroxol hydrochloride and acetylcysteine on lung injury caused by seawater submersion;4.To speculate the protective mechanism of ambroxol hydrochloride and acetylcysteine on seawater submersion induced lung injury;The first part Methods:The healthy SD rats were divided into 4 groups,including 8 in the normal control group(group A),24 in the seawater submersion group(group B),24 in the seawater submersion + ambroxol hydrochloride treatment group(group C),and 24 in the seawater submersion + acetylcysteine treatment group(group D).Among them,seawater group,ambroxol group and acetylcysteine group were divided into 3subgroups according to the time points of sampling and death after modeling,24 in each group were subdivided into 3 subgroups: 8 in each group 0.5 h after modeling,8in each group 2 h after modeling,and 8 in each group 4 h after modeling.In this way,80 rats were divided into 4 groups(Group A,Group B0.5,group B2,group B4,group C0.5,group C2,group C4,group D0.5,group D2,group D4),with 8 rats in each subgroup.After anesthesia,model B group and Treatment group C and D were intubated through the endotracheal tube and injected with 2ml/kg of the prescribed seawater.C treatment group was intraperitoneally injected with ambroxol hydrochloride50mg/kg 2 minutes before seawater injection.Treatment group D received intraperitoneal injection of 150mg/kg acetylcysteine 2 minutes before seawater injection.Group B was intraperitoneally injected with 3ml/kg saline of the same volume2 minutes before seawater injection.A Control group was only anesthetized with endotracheal intubation and intraperitoneal injection of equal volume normal saline at3ml/kg.After modeling,10 subgroups were sacrificed at different time points.Pa O2 and Pa CO2 in the arterial blood gas analysis of each subgroup were detected,as well as the lung wet-dry ratio representing the lung moisture content.Results:1.Model: The lung water content of rats increased and blood oxygen decreased to below 60 mm Hg,respiratory rate changed and moist rhonchus in both lungs indicated the formation of pulmonary edema,which successfully simulated the seawater submersion lung injury model;During the modeling process,13 rats died,which occurred within 10 minutes,with a mortality rate of 15%,including 4 rats in the model group,5 rats in the ambroxol group and 4 rats in the acetylcysteine group.2.Pa O2:0.5 h after seawater perfusion,the model group,ambroxol group and acetylcysteine group all showed significant decrease in arterial Pa O2,which was significantly different from the control group(P<0.05).There was no significant difference between model group,ambroxol group and acetylcysteine group(P>0.05).2h after perfusion,the arterial Pa O2 of ambroxol group and acetylcysteine group increased significantly,and the values were close to those of the control group,with no significant difference from the control group(P>0.05),and there was no difference between ambroxol group and acetylcysteine group(P>0.05).The recovery of Pa O2 in the model group was slow,which was significantly different from that in the control group(P<0.05).4 h after perfusion,Pa O2 in the model group,ambroxol group and acetylcysteine group all returned to normal,with no significant difference from the control group(P>0.05).3.Pa CO2: after statistical analysis,there was no significant difference in the value of Pa CO2 among the 10 subgroups(P>0.05).4.Lung water content: 0.5 h after modeling,lung water content in model group,ambroxol group and acetylcysteine group increased significantly,with statistically significant difference from the control group(P<0.05).There was no difference among model group,ambroxol group and acetylcysteine group(P>0.05).At 2 h after modeling,the lung water content of ambroxol group and acetylcysteine group decreased compared with 0.5 h(P<0.05).There was no significant difference between the 2-hour lung water content in the model group and the 0.5-hour lung water content(P>0.05).The lung water content of ambroxol group and acetylcysteine group was lower than that of model group(P<0.05).There was no significant difference between ambroxol group and acetylcysteine group(P>0.05).At 4 h after modeling,there was no significant difference between control group,model group,ambroxol group and acetylcysteine group(P>0.05).Conclusion:1.This experiment innovation,drowned rat model: the breath tube intubation and after intubation with seawater 2 ml/kg method makes lung water content increased significantly,changes in respiratory frequency,thick wet lung sound,and the blood oxygen reduced to less than 60 MMHG,building process of cuhk rat mortality 15%,no difference between the distribution of dead rats in each group,show that the new method successfully create a seawater drowning pulmonary edema model.2.Blood gas analysis and lung water content of model group,ambroxol group and acetylcysteine group were compared at each time point.It was concluded that ambroxol hydrochloride and acetylcysteine could both improve the hypoxemia of seawater submersion pulmonary edema and reduce pulmonary edema,making the recovery of the treatment group faster than that of the model group,with significant difference at the 2-hour modeling node.There was no significant difference between ambroxol group and acetylcysteine group.The second part Methods:According to the above method,the lung tissues were sacrificed and taken 2 hours after the modeling.A total of 53 lung tissue samples were obtained: 8 in the control group,15 in the model group,15 in the ambroxol group and 15 in the acetylcysteine group.The right upper lung was made into histopathological section for microscopic observation.The lung tissue homogenate was prepared from the right middle and lower lung,and the contents of malondialdehyde,TNF-A,VEGF and HIF-1A in the homogenate were detected.Results:1.Malondialdehyde content in lung tissue homogenate There was no significant difference between the acetylcysteine group and the control group(P>0.05).Malondialdehyde content in model group and ambroxol group was higher than that in control group and acetylcysteine group(P<0.05).Ambroxol group was lower than model group(P<0.05).2.TNF-A content in lung tissue homogenate There was no significant difference in TNF-a content in lung homogenate between the control group,model group,ambroxol group and acetylcysteine group after 2 h modeling(P>0.05).3.VEGF content in lung tissue homogenate The contents of VEGF in lung homogenate of model group,ambroxol group and acetylcysteine group were all higher than those of control group(P<0.05).VEGF content in acetylcysteine group was lower than that in model group and ambroxol group(P<0.05).There was no significant difference between the model group and ambroxol group(P>0.05).4.Hif-1a content in lung tissue homogenate Hif-1a content in lung homogenate of model group,ambroxol group and acetylcysteine group was higher than that of control group(P<0.05).The hi F-1A content in acetylcysteine group was lower than that in model group and ambroxol group(P<0.05).There was no significant difference between the model group and ambroxol group(P>0.05).5.Pulmonary histopathological observation for 2 hours after modeling Gross specimens: The gross specimens of the lungs in the normal control group were between white and pink,with tender texture and subtle pleural folds.In the model group,the lung was obviously swollen,enlarged,and heavy,with patchy congestion and scattered punctate hemorrhage,especially in the back and lower lung.Ambroxol treatment group and acetylcysteine group were slightly lighter than the model group and still different from the control group.The gross appearance of lung specimens in ambroxol group and acetylcysteine group was not significantly different.Microscopically,the normal control group had clear lung structure,complete alveolar septa,no fluid in the alveolar cavity,and no telangiectasia.Thickening and edema of bronchioles were observed in model group.Some alveoli collapsed,some alveoli overexpanded,visible bronchial and alveolar epithelial cells shed into the lumen,alveolar cavity can be seen red light stained fluid and red blood cells,rare neutrophils and lymphocytes;Alveolar septa thickened and fractured with occasional mononuclear macrophages.Telangiectasia and congestion.The ambroxol group and acetylcysteine group had less damage than the model group.There was no significant difference between acetylcysteine group and ambroxol group.Conclusion:1.The damage factors of seawater submergence pulmonary edema model in this study include: direct damage of seawater;Capillary permeability increased;Peroxidation injury.There was no evidence that the inflammatory factor TNF-A was involved in the injury.2.Acetylcysteine reduces the expression of HIF-1A and VEGF in lung tissues and malonaldehyde content,reduces capillary permeability and antioxidant damage,reduces the leakage of intravascular fluids,alleviates pulmonary edema,and cures seawater submersion pulmonary edema.3.Ambroxol hydrochloride is effective in the treatment of seawater submersion pulmonary edema,and there is no statistically significant difference between its effect and that of acetylcysteine;Ambroxol can reduce malondialdehyde in the lung homogenate of rats in submersion model,and it is speculated that the mechanism of improving seawater submersion pulmonary edema is related to anti-peroxidation injury. |
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