蛋白酶抑制剂对内毒素致大鼠急性肺损伤的保护作用

目的:静脉应用蛋白酶抑制剂以了解其对内毒素所致的大鼠肺损伤的保护作用及其机制.方法:雄性Wistar大鼠32只,体重(250～270 g),分为对照组(C,n=8)、内毒素组(A,n=8)、大剂量治疗组(U,n=8)及小剂量治疗组(V,n=8),除对照组外,其他组均给予内毒素(5 mg/kg),治疗组同时给予内毒素和乌司他丁注射(U组100 000 u/kg,V组50 000 u/kg).2 h后测定血清内皮素,进行动脉血气分析,取肺组织观察大体标本形态和光镜下的组织病理形态,测定肺组织血管通透性变化、湿/干质量比值、髓过氧化物酶活性、脂质过氧化产物[丙二醛(malonaldehyde,MDA)和共轭二烯(conjugated-diene,C-diene)].结果:光镜下可见对照组肺组织学正常,内毒素组肺间质弥漫性出血,肺泡腔内可见大量粒细胞聚集、浸润,并可见弥漫性肺泡间隔增厚,而乌司他丁治疗组上述病理表现明显减轻.肺组织湿/干质量比值和每克肺组织伊文思蓝含量在内毒素组分别为(5.41±0.06)和(27.64±2.48)μg,对照组分别为(4.95±0.08)和(12.99±2.83)μg,组间比较差异有统计学意义;U组为(5.0±0.05)和(19.47±2.09)μg;V组为(4.98±0.06)和(21.44±3.12)μg,明显低于内毒素组,U组和V组间差异无统计学意义.血清内皮素及髓过氧化物水平内毒素组分别为(948.23±103.45)u/g和(152.90±8.41)u/g,高于对照组的(729.38±88.64)u/g和(54.62±15.49)u/g,U组为(633.27±93.27)u/g和(119.40±11.32)u/g,V组为(671.87±105.45)u/g和(129.55±9.57)u/g,则低于内毒素组,U组和V组间差异无统计学意义.肺组织脂质过氧化产物水平内毒素组[(MDA(73.95±4.62)nmol/g;C-diene(10.96±0.81)nmol/g]明显高于对照组[MDA(39.65±6.21)nmol/g;C-diene(3.34±0.51)nmol/g],治疗组[U组:MDA(51.26±5.56)nmol/g,C-diene(7.59±0.84)nmol/g;V组:MDA(59.87±4.62)nmol/g,C-diene(8.79±0.45)nmol/g]则较内毒素组明显降低,MDA水平U组低于V组.结论:乌司他丁明显降低肺组织的炎症反应,减轻肺组织的损害,对内毒素所致大鼠肺损伤具有一定的保护作用.

Inhibitory effects of protease inhibitor on endotoxin-induced acute lung injury in rats

OBJECTIVE: To investigate the effects of protease inhibitor on lipopolysaccharide-induced acute lung injury in rats and its possible mechanisms. METHODS: Thirty-two male Wister rats, weighting 250-270 g, were divided into four groups randomly. C, normal controls (n=8); A: acute lung injury group (n=8), receiving intravenous endotoxin (lipopolysaccharide O55:B5, LPS 5 mg/kg); V, low-dose group (n=8), U, high-dose intervention group (n=8, receiving Ulinastatin 50,000 U/kg and 100,000 U/kg respectively and LPS 5 mg/kg). The specimens were collected 2 hours later, We observed the following changes: blood gas analysis, the lung wet/dry weight ratio, the pulmonary vascular permeability, histological manifestations, lung tissue myeloperoxidase activity, plasma endothelin-1, lung tissue malonaldehyde and conjugated-diene. RESULTS: Compared with Group C, the lungs of the rats in Group A had significant hyperemia and spotted hemorrhage. The inflammatory granulocyte infiltrating, diffused alveolar septum thickening and spotted hemorrhage were observed in pathological examinations. The lung wet/dry weight ratio and Evans Blue content (per gram) increased significantly in group A [(5.41+/-0.06), (27.64+/-2.48) microg] compared with group C [(4.95+/-0.08), (12.99+/-2.83) microg], in the intervention groups (U: 5.0+/-0.05, 19.47+/- 2.09; V: 4.98+/-0.06, 21.44+/-3.12) however the difference was not significant between the intervention groups; The plasma endothelin-1 and lung tissue myeloperoxidase activity increased significantly in group A [(948.23+/-103.45) u/g, (152.90+/-8.41) u/g] compared with group C [(729.38+/-88.64) u/g ], [(54.62+/-15.49) u/g] but intervention groups [U: (633.27+/-93.27) u/g, (119.40+/-11.32) u/g; V: (671.87+/-105.45) u/g, (129.55+/-9.57) u/g] decreased significantly compared with group A, no significant difference between intervention groups; lung tissue Lipid-peroxide (malonaldehyde, MDA and conjugated-diene, C-diene) increased significantly in group A [MDA: (73.95+/-4.62) nmol/g; C-diene: (10.96+/-0.81) nmol/g] compared with group C [MDA: (39.65+/-6.21) nmol/g; C-diene: (3.34+/-0.51) nmol/g], intervention groups [U: MDA: (51.26+/-5.56) nmol/g, C-diene: (7.59+/-0.84) nmol/g; V: MDA: (59.87+/-4.62) nmol/g, C-diene: (8.79+/-0.45) nmol/g] decreased significantly compared with group A. MDA decreased significantly in group U compared with group V. CONCLUSION: The protease inhibitor, Ulinastatin, may decrease inflammatory reaction and further decrease lung damage induced by LPS in rats, all indicating protection of protease inhibitor against acute lung injury.