High tidal volume ventilation activates Smad2 and upregulates expression of connective tissue growth factor in newborn rat lung

High tidal volume (V(T)) ventilation plays a key role in ventilator induced lung injury and bronchopulmonary dysplasia. However, little is known about the effect of high V(T) on expression of growth factors that are critical to lung development. In a previous study, we demonstrated that connective tissue growth factor (CTGF) inhibits branching morphogenesis. In this study, we investigated the effect of high V(T) on CTGF expression in newborn rat lungs. Newborn rats were ventilated with normal V(T) (10 mL/kg) or high V(T) (25 mL/kg) for 6 h. Nonventilated animals served as controls. We found that high V(T) upregulated CTGF expression. To identify the potential signaling pathways mediating high V(T) induction of CTGF, newborn rats were ventilated with high V(T) for 1 or 3 h. Temporal expression of TGF-betas, p-Smad2, Smad7, and CTGF was analyzed. High V(T) ventilation did not change gene expression of TGF-betas and Smad7 but induced rapid and sustained expression of p-Smad2 that precedes increased CTGF expression. CTGF and p-Smad2 were localized in bronchiolar epithelial cells, alveolar walls and septa. These data suggest that high V(t) ventilation activates the Smad2 pathway, which may be responsible for downstream induction of CTGF expression in newborn rat lungs.     

Alterations of surfactant pools in fetal and newborn rat lungs

Preparation by the developing alveolar epithelium for the transition to air breathing and surfactant secretion at birth are critical components of neonatal survival. We combined morphometric analysis and biochemical assays of lung phospholipids to measure the amount and redistribution of lung surfactant during the perinatal period of rats. Within 10 min of the start of air breathing, there was a small increase in type II cell lamellar body content by morphometric and biochemical estimates. By 24 h, the whole lung and alveolar extracellular pool surfactant lipid had substantially increased. Subfractionation of the alveolar surfactant pool obtained at four times, from birth to 24 h of life, demonstrated a 20-fold increase in the ratio of phospholipid in a tubular myelin-rich fraction compared to a unilamellar vesicle-rich fraction. We conclude that packaging of surfactant may be very active immediately postbirth. Our results also indicate a major shift in the physical forms of extracellular surfactant during the first hours of air breathing.     

高浓度氧对新生大鼠肺血管内皮生长因子及其受体表达的影响

目的研究持续吸入75%氧对新生大鼠肺血管内皮生长因子(vascular endothelial growth factor,VEGF)及其受体(VEGFR1和VEGFR2)表达的影响,探讨较高浓度吸氧对肺血管发育的影响及与支气管肺发育不良(bronchopulmonary dysplasia,BPD)的关系。方法新生足月Sprague-Dawley大鼠48只,随机分为对照组和实验组。实验组生后12h开始持续吸入75%氧气。分别于实验开始后的7d、14d和21d处死留取肺组织标本,苏木精-伊红染色观察病理改变,免疫组化检测VEGF及其受体蛋白表达,RT-PCR检测其mRNA表达。结果实验组大鼠肺组织结构发生类似"新型"BPD的病理改变。75%氧暴露21d时,VEGF(10.9±2.7vs30.8±6.4)、VEGFR1(5.4±1.4vs15.6±3.4)和VEGFR2(11.3±2.6vs21.7±4.5)的蛋白表达均较对照组减少(P<0.05);VEGF(1.6vs3.3)、VEGFR1(0.4vs6.6)及VEGFR2(0.5vs4.9)的mRNA表达均较对照组减少(P<0.05)。结论在新生大鼠中,长时间吸入较高浓度氧可能通过抑制肺血管发育导致BPD的发生。     

高浓度氧对新生大鼠肺血管内皮生长因子及其受体表达的影响

目的:研究持续吸入75%氧对新生大鼠肺血管内皮生长因子（vascular endothelial growth factor,VEGF）及其受体（VEGFR1和VEGFR2）表达的影响,探讨较高浓度吸氧对肺血管发育的影响及与支气管肺发育不良（bronchopulmonary dysplasia,BPD）的关系。方法:新生足月Sprague-Dawley大鼠48只,随机分为对照组和实验组。实验组生后12 h开始持续吸入75%氧气。分别于实验开始后的7 d、14 d和21 d处死留取肺组织标本,苏木精-伊红染色观察病理改变,免疫组化检测VEGF及其受体蛋白表达,RT-PCR检测其mRNA表达。结果实验组大鼠肺组织结构发生类似“新型”BPD的病理改变。75％氧暴露21 d时,VEGF（10.9±2.7 vs 30.8±6.4）、VEGFR1（5.4±1.4 vs 15.6±3.4）和VEGFR2（11.3±2.6 vs 21.7±4.5）的蛋白表达均较对照组减少（P<0.05）;VEGF（1.6 vs 3.3）、VEGFR1（0.4 vs 6.6）及VEGFR2（0.5 vs 4.9）的mRNA表达均较对照组减少（P<0.05）。结论:在新生大鼠中,长时间吸入较高浓度氧可能通过抑制肺血管发育导致BPD的发生。［中国当代儿科杂志,2009,11（11）：927-930］     

小潮气量常规机械通气对发育肺生长因子和炎症因子表达的影响

目的：探讨小潮气量常规机械通气对发育肺生长因子（GFs）和炎症因子表达的影响。方法：分别将早产猪（85％孕龄）、足月新生猪及幼猪（4~5周龄）随机分为机械通气组（MV组）和自主呼吸对照组（NMV组）。调节呼吸机参数,使呼出气潮气量维持在6～8 mL/kg,机械通气6 h（早产猪）或24 h（新生猪、幼猪）后检测肺组织GFs（PDGF-B,IGF-I,KGF,HGF,VEGF,TGF-β1）及炎症因子（IL-1β,IL-6,IL-8,TNF-α）mRNA表达,免疫组化方法观察GFs蛋白表达与分布。多组间比较用单因素方差分析或Kruskal-Wallis检验,两组间比较用t检验或Mann-Whitney U检验。结果：①在早产组,MV组PDGF-B,IL-1β,IL-6,IL-8 mRNA水平较NMV组增高（5.11±0.10 vs 4.88±0.01, 4.95±0.27 vs 4.08±0.37, 4.76±0.27 vs 4.00±0.28, 5.31±0.57 vs 4.15±0.46; P<0.01或0.05）,IGF-I mRNA水平降低（3.54±0.13 vs 3.80±0.11; P<0.01）;②在足月新生组及幼年组,MV组GFs及炎症因子mRNA水平较NMV组差异均无显著性。结论： 生后早期机械通气干扰了早产肺GFs的表达,并诱发促炎因子表达,促进了肺损伤的发生;但对足月和幼年肺GFs和炎症因子表达无明显影响。     

宫内炎性预敏和生后高氧暴露对早产大鼠肺Bax和Bcl-2基因表达和肺细胞增殖及凋亡的影响

目的 观察宫内炎性预敏及生后60%氧暴露对肺增殖性细胞核抗原(PCNA)及肺细胞凋亡影响的动态变化规律及Bcl-2家族中Bax、Bcl-2基因的表达对肺细胞凋亡的调控作用;探讨其与新型支气管肺发育不良(BPD)发病机制之间的关系.方法早产大鼠随机分为生理盐水+高氧组、脂多糖(LPS)+高氧组、LPS组和正常对照组,于生后第1、7和14天利用简单随机抽样方法取8只,采用免疫组织化学染色方法检测各组肺组织PCNA表达水平及脱氧核糖核酸转移酶介导的细胞凋亡标记技术(TUNEL)和逆转录聚合酶链反应技术(RT-PCR)检测各组肺组织凋亡和Bax、Bcl-2基因表达水平.结果 ①PCNA的表达:LPS组和生理盐水+高氧组在生后第1天表达明显低于对照组(LPS组:0.18±0.01;生理盐水+高氧组:0.53±0.11;对照组:1.16±0.31;P=0.005,0.021);LPS+高氧组在生后第14天明显低于其他3组(对照组:0.89±0.22;LPS组:1.03±0.07;生理盐水+高氧组:0.96±0.16;LPS+高氧组:0.47±0.08;P=0.048,0.019,0.030).②凋亡指数(AI):LPS组在生后第1天明显高于对照组(17.73±2.21 vs 7.16±0.31,P=0.021);生理盐水+高氧组在生后第7天最高;LPS+高氧组在生后第14天表达明显高于其他3组(对照组:20.53±4.51;LPS组:13.99±1.69;生理盐水+高氧组:35.08±4.96;LPS+高氧组:49.92±7.93;P=0.005,0.002,0.048).③BaxmRNA的表达:LPS组在生后1 d明显高于其他3组(LPS组:0.73±0.06;对照组:0.16±0.03;生理盐水+高氧组:0.23±0.03;LPS+高氧组:0.24±0.13;P=0.001,0.002,0.002);生理盐水+高氧组在生后第7天表达明显高于对照组(0.58±0.06 vs 0.19±0.05,P=0.002);LPS+高氧组在出生后第14天明显高于对照组(0.58±0.01 vs 0.29±0.09,P=0.009).④Bcl-2 mRNA的表达:LPS组在生后在第1天明显低于其他3组(LPS组:0.18±0.02;对照组:0.41±0.09;生理盐水+高氧组:0.48±0.03;LPS+高氧组:0.59±0.05;P=0.019,0.007,0.012);生理盐水+高氧组及LPS+高氧组在生后第7天明显低于对照组(0.28±0.05/0.21±0.02 vs 0.49±0.09,P=0.02,0.008).结论 宫内炎性预敏及生后高氧暴露可抑制肺细胞增殖,可能通过提高Bax/Bcl-2的表达途径使肺组织细胞过度凋亡,进而导致BPD的发生.     

新生儿高频振荡通气时呼出气潮气量与动脉二氧化碳分压的研究

目的 探讨新生儿高频振荡通气(HFOV)时呼出气潮气量与动脉二氧化碳分压(PaCO2)变化的关系.方法 对应用HFOV的重症呼吸衰竭新生儿,监测记录PaCO2、呼出气潮气量(VTe)、呼吸机频率(F)、平均气道压(MAP)、振幅(ΔP)及吸入氧浓度(FiO2)等指标,并进行相关性分析.结果 共46例患儿接受HFOV治疗,平均胎龄(36.37 ± 3.53)周,出生体质量(2.76 ± 7.77)kg.不同PaCO2组( ＜ 35 mmHg、35 ～ 45 mmHg、46 ～ 55 mmHg、＞ 55 mmHg)对应VTe/kg平均值分别为(2.20 ± 0.40)ml/kg、(1.96 ± 0.46)ml/kg、(1.71 ± 0.44)ml/kg、(1.21 ± 0.33)ml/kg,组间比较差异有统计学意义(χ2 ＝ 85.74,P ＜ 0.05),Vte/kg与PaCO2呈负相关(r ＝ -0.59,P ＜ 0.05).当PaCO2于正常范围(35 ～ 45 mmHg),MAP为8 ～ 10 cmH2O、11 ～ 13 cmH2O、14 ～ 16 cmH2O、＞ 16 cmH2O时,对应VTe/kg平均值分别为(1.73 ± 0.33)ml/kg、(1.90 ± 0.39)ml/kg、(2.19 ± 0.54)ml/kg、(2.53 ± 0.53)ml/kg,组间比较差异有统计学意义(χ2 ＝ 18.96,P ＜ 0.05),VTe/kg和MAP呈正相关(r ＝ 0.43,P ＜ 0.05).经多元线性回归分析逐步法建立回归方程:PaCO2 ＝ -13 VTe/kg + 4.32 F + 0.13 FiO2 + 19.68(r ＝ 0.68,r2 ＝ 0.47,P ＜ 0.05).结论 新生儿高频振荡通气时VTe/kg与PaCO2呈负相关,PaCO2正常范围时VTe/kg和MAP呈正相关;高频振荡通气时监测VTe可作为调控PaCO2的参考.     

Low oxygen exposure does not cause pulmonary injury in the newborn rat

BACKGROUND: Two recent studies have suggested that low levels of supplemental inspired oxygen may cause lung injury in preterm infants. AIMS: To assess lung injury of newborn rats exposed to 14 days of low-level variation of oxygen. STUDY DESIGN: Four groups were compared with 12 animals per group and 4 lung sections per animal. These were, a control group raised in room air and three groups raised in levels of inspired oxygen fluctuating around the following mean values: group Lo (mean FiO(2) 0.179), group N (mean FiO(2) 0.213), and group Hi (mean FiO(2) 0.247). The degree of oxygen variability was identical for each group. Lungs were inflated at 20 cm H(2)O, fixed and stained with H and E and Millers Elastin. SUBJECTS: Sprague Dawley albino newborn rats. OUTCOME MEASURES: Random alveolar areas were studied and analysed using imaging software to assess total amount of tissue and elastin, number of secondary septa, and mean linear intercept. RESULTS: There were no significant differences between the three experimental oxygen groups and the control group in terms of lung/body weight ratio and the measured markers of lung development. CONCLUSION: We conclude that low-level oxygen supplementation during early lung development does not affect alveolar development in the newborn rat.     

宫内炎性预敏及生后高氧暴露对早产大鼠肺血管内皮生长因子及其受体表达的影响

目的观察宫内炎性预敏及生后高氧暴露对早产大鼠肺血管内皮生长因子（VEGF）及其受体表达的影响,探讨其与新型支气管肺发育不良（BPD）发病机制之间的关系。方法早产大鼠随机分为生理盐水＋高氧组、LPS＋高氧组、LPS组和正常对照组,于生后第1、7和14天随机取8只,行HE染色,观察肺组织形态学结构,做辐射状肺泡计数（RAC）采用Western blot和RT-PCR方法检测各组肺组织VEGF及其受体Fit-1和Flk-1蛋白及mRNA表达水平。结果（1）正常对照组和LPS组在生后1～14d随鼠龄增加,RAC逐渐增多,但LPS组在生后第1～14天RAC均低于对照组（P分别=0．029,0．013,0．009）;生理盐水＋高氧组和LPS＋高氧组则随鼠龄增加RAC逐渐下降,LPS＋高氧组至生后14dRAC低于其他三组（P分别=0.000,0.002,0.012）。（2）VEGF及其受体Flk-1蛋白的表达与其相应肺组织RAC变化规律基本一致。而Fit-1表达在四组中均随鼠龄增加而呈增高趋势。（3）VEGF及其受体mRNA表达规律与其蛋白表达强度变化规律基本一致。结论宫内炎性预敏及生后高氧暴露可能是导致新型BPD发生的重要因素。     

前内皮素原mRNA在新生鼠肺出血发生过程中肺内的表达及作用

目的探讨前内皮素原mRNA(preproendothelin-1 mRNA,ppET-1mRNA)在新生鼠肺出血发生过程中肺组织中的表达。方法生后7～8d的Wister新生鼠,随机分为空气组(C)、低氧组(H)、低温缺氧组(HH)、低温缺氧后常氧复温组(HHR)、低温缺氧后高氧复温组(HHRO2)。C组置常温室内,H组置低氧箱内6h,吸入氧气浓度5%～6%,HH组同H组,并置于(10±1℃)冰箱内6h,HHR组低温缺氧过程同HH组,随后常氧下复温2h,HHRO2组同HHR组但复温时吸入气氧浓度>95%。各组取肺组织,观察肺大体,切片HE染色观察肺组织病理学改变,逆转录——聚合酶链反应(RT-PCR)方法检测肺组织中ppET-1mRNA表达。结果H组、HH组、HHR组和HHRO2组肺大体均呈现水肿,HH组、HHR组和HHRO2组可见点状、局灶性至弥漫性出血;光镜下组织学改变包括肺水肿(肺泡及间隔水肿)、肺泡扩大、间隔断裂、肺泡融合及出血,HHRO2组最严重;ppET-1mRNA在H组、HH组、HHRO2组表达量增高(分别为0.706±0.184、0.641±0.172、0.673±0.246),与C组(0.363±0.216)比较P均<0.01。结论在新生鼠肺出血发生过程中,肺组织中ppET-1mRNA呈高表达状态,在肺出血发生过程中起了重要的作用。     

Evidence for decreased lipofibroblast expression in hypoplastic rat lungs with congenital diaphragmatic hernia

Purpose

Pulmonary hypoplasia (PH) is a serious condition in newborns with congenital diaphragmatic hernia (CDH). Lipid-containing interstitial fibroblasts (LIFs) play an essential role in fetal lung maturation by stimulating alveolarization and lipid homeostasis. In rodents, LIFs are first evident during the canalicular phase of lung development with a significant increase over the last 4 days of gestation. Adipocyte differentiation-related protein (ADRP), a functional lipogenic molecular marker characterizing LIFs, is highly expressed in fetal lungs during this critical time period. We hypothesized that LIF expression in hypoplastic rat lungs is decreased in the nitrofen-induced CDH model, which is accompanied by reduced alveolar ADRP expression and lipid content.

Methods

On embryonic day 9.5 (E9.5), time-mated rats received either nitrofen or vehicle. Fetuses were sacrificed on selected time points E18.5 and E21.5, and dissected lungs were divided into controls and CDH-associated PH. Pulmonary gene expression levels of ADRP were determined by quantitative real-time polymerase chain reaction. ADRP immunohistochemistry and oil red O staining were used to assess pulmonary protein expression and lipid content. Immunofluorescence double staining for alpha smooth muscle actin, which is known to be absent in LIFs, and lipid droplets was performed to evaluate the pulmonary expression of this specific subset of fibroblasts.

Results

Relative mRNA expression of ADRP was significantly reduced in lungs of CDH-associated PH on E18.5 and E21.5 compared to controls. ADRP immunoreactivity and lipid staining were markedly diminished in alveolar mesenchymal cells of CDH-associated PH on E18.5 and E21.5 compared to controls. Confocal laser scanning microscopy demonstrated markedly decreased LIF expression in alveolar interstitium of CDH-associated PH on E18.5 and E21.5 compared to controls.

Conclusion

Decreased pulmonary LIF expression during late gestation suggests impaired LIF functioning in the nitrofen-induced CDH model, which may cause disruption in fetal alveolarization and lipid homeostasis, and thus contribute to the development of PH.     

Meconium aspiration stimulates cyclooxygenase-2 and nitric oxide synthase-2 expression in rat lungs

To study the impact of meconium aspiration on the biosynthesis of prostaglandins and nitric oxide, we investigated the effects of intratracheal meconium instillation on the expression of cyclooxygenase-1 (COX-1) and -2 (COX-2) and endothelial (NOS-3) and inducible (NOS-2) nitric oxide synthase in rat lungs. Anesthetized, tracheotomized, and ventilated rats received 3 mL/kg human meconium suspension intratracheally (n = 19), and 14 control rats received an equal volume of saline. Ten rats were pretreated with indomethacin, and 13 rats were pretreated with dexamethasone. The lungs were ventilated with 70% oxygen for 3 h after the insult, and the level of COX-1, COX-2, NOS-2, and NOS-3 mRNA in lung tissue was analyzed by Northern blot hybridization. Furthermore, the expression and localization of the enzyme proteins was analyzed by immunohistochemistry. COX-1 and NOS-3 were clearly expressed in the lungs of control rats, whereas the level of COX-2 and NOS-2 expression was minimal. Meconium administration did not affect the expression of COX-1, but COX-2 expression was up-regulated in the respiratory epithelium and alveolar macrophages. Meconium also induced up-regulation of NOS-2 in the pulmonary epithelium, vascular endothelium, and macrophages. Indomethacin pretreatment did not affect the enzyme expressions, whereas dexamethasone administration significantly inhibited the meconium-induced COX-2 and NOS-2 up-regulation. Our data thus indicate that intrapulmonary meconium up-regulates lung COX-2 and NOS-2 gene expression, suggesting an important role for prostaglandins and nitric oxide in the meconium aspiration-induced pulmonary inflammation and hemodynamic changes.     

Maternal nicotine effects on vascular endothelial growth factor expression and morphometry in rat lungs

Aims

Maternal smoking during pregnancy may impair pulmonary function in infants, and the exact mechanisms underlying these changes are unknown. We evaluated the effects of maternal nicotine exposure on lung VEGF expression and morphometry during the postnatal period in rats.

Methods and results

Timed pregnant Sprague–Dawley rats were injected subcutaneously with nicotine at a dose of 2 mg/kg/day from Day 3 to Day 21 of gestation. A control group was injected with saline. Body weight, lung weight, and lung volume were comparable between control and nicotine-exposed rats. Plasma vascular endothelial growth factor (VEGF) levels and lung VEGF mRNA expression decreased with advancing age, and nicotine exposure insignificantly decreased plasma VEGF levels and lung VEGF mRNA expression, compared with the control rats during the study period. Nicotine exposure caused a significant decrease in vascular endothelial growth factor receptor (VEGFR)-2 mRNA expression, compared with the level of the control rats on Postnatal Day 1. On Postnatal Day 1, nicotine-exposed rats exhibited a significantly lower volume fraction of alveolar airspace and alveolar surface area and a significantly higher alveolar wall volume fraction than did the control rats.

Conclusions

Maternal nicotine exposure during pregnancy decreases VEGF and VEGFR-2 mRNA expression and alters lung structure in the lungs of postnatal rats. Because angiogenesis is vital for alveolarization during normal lung development, these results suggest that decreased VEGF expression might be involved in the structural alterations of the developing lung after exposure to antenatal nicotine.     

Effects of positive end-expiratory pressure, inhaled nitric oxide and surfactant on expression of proinflammatory cytokines and growth factors in preterm piglet lungs

We hypothesized that imbalance of proinflammatory cytokines and growth factors (GFs) in immature lungs of early postnatal life may be affected by protective ventilation strategy, and evaluated correlations of these aspects. Preterm neonate piglets were mechanically ventilated with low tidal volume and 5-6 or 10-12 cm H2O positive end-expiratory pressure (PEEP) with or without surfactant and inhaled nitric oxide (iNO) for 6 h, followed by biochemical, biophysical, and histopathological assessment of lung injury severity. Compared with surfactant and the control, iNO combined with lower PEEP exerted better oxygenation, lower activity of myeloperoxidase, lower expression of mRNA of interleukin (IL)-1beta, IL-6, IL-8, and platelet derived growth factor-B (PDGF-B), but higher expression of insulin-like growth factor-I (IGF-I), whereas that of tumor necrosis factor-alpha, keratinocyte GF, hepatocyte GF, vascular endothelial growth factor, and TGF-beta1 had no or modest changes. IL-1beta, IL-6 mRNA were closely correlated to PDGF-B mRNA and myeloperoxidase, but inversely to IGF-I mRNA, Pao2/FiO2 and dynamic lung compliance at 6 h. These results indicate that the association of lower PEEP and iNO may be more protective than surfactant on preventing lung injury and facilitating reparation by affecting the expression of proinflammatory cytokines and GFs.     

Partial liquid ventilation versus conventional mechanical ventilation with high PEEP and moderate tidal volume in acute respiratory failure in piglets

This prospective randomized pilot study aimed to test the hypotheses that partial liquid ventilation combined with a high positive end-expiratory pressure (PEEP) and a moderate tidal volume results in improved gas exchange and lung mechanics without negative hemodynamic influences compared with conventional mechanical ventilation in acute lung injury in piglets. Acute lung injury was induced in 12 piglets weighing 9.0 +/- 2.4 kg by repeated i.v. injections of oleic acid and repeated lung lavages. Thereafter, the animals were randomly assigned either to partial liquid ventilation (n = 6) or conventional mechanical ventilation (n = 6) at a fractional concentration of inspired O(2) of 1.0, a PEEP of 1.2 kPa, a tidal volume < 10 mL/kg body weight (bw), a respiratory rate of 24 breaths/min, and an inspiratory/expiratory ratio of 1:2. Perfluorocarbon liquid 30 mL/kg bw was instilled into the endotracheal tube over 10 min followed by 5 mL/kg bw/h. Continuous monitoring included ECG, mean right atrial, pulmonary artery, pulmonary capillary, and arterial pressures, arterial blood gas, and partial pressure of end-tidal CO(2) measurements. When compared with control animals, partial liquid ventilation resulted in significantly better oxygenation with improved cardiac output and oxygen delivery. Dead space ventilation appeared to be lower during partial liquid ventilation compared with conventional mechanical ventilation. No significant differences were observed in airway pressures, pulmonary compliance, and airway resistance between both groups. The results of this pilot study suggest that partial liquid ventilation combined with high PEEP and moderate tidal volume improves oxygenation, dead space ventilation, cardiac output, and oxygen delivery compared with conventional mechanical ventilation in acute lung injury in piglets but has no significant influence on lung mechanics.     

高氧对新生大鼠肺血管发育及肺组织血管生成素1表达的影响

目的 观察持续吸入85％氧气对新生大鼠肺血管发育和肺组织血管生成素1(Ang-1)表达的影响,探讨高氧肺损伤新生大鼠的肺血管发育情况及可能的发生机制.方法 将96只新生SD大鼠在生后6h内,随机分为高氧组和空气组,高氧组将大鼠置于自制密闭氧箱,FiO2=0.85.在实验3、7、14d每组各随机取16只处死,采集标本.采用HE染色进行肺组织形态学分析,放射状肺泡计数评价肺泡化程度,肺动脉钡剂造影及肺动脉密度检测评价肺血管的发育,免疫组织化学法检测肺组织Ang-1的表达,荧光定量PCR和Western blot技术检测肺组织Ang-1的mRNA和蛋白表达水平.结果 (1)新生大鼠高氧暴露14 d,肺组织的病理表现与早产儿支气管肺发育不良(BPD)的病理表现相似.(2)高氧组7 d RAC值显著低于空气组[(10.55±0.13):(11.74 ±0.19),P＜0.05],在14d时差异更显著[(12.47±0.05):( 15.03±0.16),P＜0.01].(3)肺动脉钡剂造影显示,高氧组14 d大鼠肺动脉主干变细,肺小动脉显影减少,肺动脉密度显著低于空气组[(3.55±0.09):(6.03±0.16),P＜0.05].(4)免疫组化染色显示,高氧组7d和14 d,肺组织Ang-1的表达均显著低于同时间点空气组[ (4.27±0.34):(3.10 ±0.29),P＜0.05,(5.65±0.49)∶(3.21±0.28),P＜0.01].(5)荧光定量PCR及Western blot结果显示,高氧组7d和14 d,Ang-1的mRNA水平显著低于空气组[(0.85±0.14)∶(0.44±0.21),P＜0.05,(0.87±0.24)∶(0.24±0.05),P＜0.01],Ang-1的蛋白水平也显著低于空气组[(0.88±0.31)∶(0.41 ±0.12),P＜0.05,(0.90 ±0.29):(0.21 ±0.06),P＜0.01].结论 持续吸入高浓度氧导致新生大鼠的肺血管发育障碍,Ang-1的表达下调可能参与了早产儿BPD血管发育受阻的发生机制.