The Anti-oxidation Effect Of Heme Oxygenase-1 On Alveolar Type Ⅱ Epithelial Cell In Rats During Acute Lung Injury

Objective To evaluate the effect of heme oxygenase-1(HO-1)on reducing injury of lungs associated with acute lung injury(ALI) and protecting typeâ…¡alveolar epithelial cell of rat after ALI.Methods Thirty-two healthy male SD rats,each weighting 180～220g,were randomly divided into four groups(n=8): group A,group B,group C,group D.The aspirin was added in the food before mold in the group C(5mg/kg.d,two days).The specific inhibitors-â…¨zinc porphyrin was added in group D,the first dose of 20μmol/kg,subcutaneous injection molding 6h ago, and then to the same dose after 3h.All the rats were anesthesitized with 10%chloral hydrate(0.35 ml/100g).Group A were given 0.15ml/kg natural solution through the femoral vein;Group B,C and D were given 0.15ml/kg oleic acid through the femoral vein.Arterial blood samples were taken from the carotid artery separately at T₁(after injection of oleic acid 30min),T₂(after injection of oleic acid 60min),T₃ (after injection of oleic acid 120min) for blood gas analysis.All the rats were killed immediately after 2 hours,opened the chest and ligated the lung door.Used 3ml frozed normal saline to lavage the left lung and collected bronchoalveolar lavage fluid(BALF) for the detection of pulmonary surfactant-associated protein A(SP-A) content.The right lung tissues were collected in 2h after OA for Lung weight/dry ratio(W/D),Specimens of lung tissue were observed for the pathological change of lung structure with optical microscope,RT-PCR methods were used to determine the expression level of HO-1mRNA in lung tissue.Results 1) PaO₂ and PaO₂/FiO₂:At the same time point,the level of PaO₂ and PaO₂/FiO₂ was significantly increased in group C than that in group B(P＜0.01).The level of PaO₂ and PaO₂/FiO₂ was significantly lower in group D than that in group B(P＜0.01),when it is the most obvious at T₃.2).PaCO₂:At the same time point,the level of PaCO₂ was significantly lower in group C than that in group B(P＜0.05).The level of PaCO₂ was significantly increased in group D than that in group B(P＜0.05),when it is the most obvious at T₃. 3).W/D:The level of W/D was significantly lower in group C than that in group B (P＜0.01).The level of W/D was significantly increased in group D than that in group B(P＜0.01),4) In group B,The structure of lung tissue in optical microscope was of very disorder,massive inflammatory cell infiltrating,alveolus capillary dilating,congestioning,alveolar wall congestioning obviously,alveolar septum widening,even massive erythrocyte appearing in alveolar space,focal atelectasis.The injury of lung tissue was significantly abated in group C than that in group B.The injury of lung tissue was significantly heavier in group D than that in group B.5) SP-A:The level of SP-A in BALF was significantly increased in group C than that in group B(P＜0.01), The level of SP-A in BALF was significantly lower in group D than that in group B (P＜0.01).The level of SP-A in blood was significantly lower in group C than that in group B(P＜0.01),The level of SP-A in blood was significantly increased in group D than that in group B(P＜0.01).6) HO-1mRNA:The level of HO-1mRNA in the lung tissue was significantly increased in group C than that in group B(P＜0.01),The level of HO-1mRNA in the lung tissue was significantly lower in group D than that in group B(P＜0.01).Conclusion HO-1 could lower pulmonary microvascular permeability after ALI injured lung,and hence,may provide better protection against the injuries.