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Acute lung injury / acute respiratory distress syndrome (Acute Lung Injury / Acute RestpiratoryDistress Syndrome, ALI / ARDS) is a severe infection, shock, trauma and burns during non-cardiac disease, pulmonary capillary endothelial cells and alveolar epithelial cells damage caused by diffuse pulmonary interstitial and alveolar edema, leading to acute hypoxic respiratory insufficiency or failure. Epidemiological survey, ALI / ARDS is a common clinical critically ill patients. According to the 1994 U.S. meeting proposed ALI / ARDS diagnostic criteria, ALI annual incidence of 18/100 000, ARDS is an annual 13 to 23/100 000. 2005 study showed ALI / ARDS incidence rates were in the annual 79/100000 and 59/100000 Tip ALI / ARDS incidence was significantly higher, significantly increased the social and economic burden, which is even with the breast cancer, AIDS, asthma, or myocardial infarction compared. Although different studies reported mortality in ARDS large differences, in general, the current ARDS mortality is still high. For 1967 to 1994, published in the International ARDS formal meta-analysis of clinical studies, 3264 cases of patients with ARDS mortality is about 50%. March 2001 to March 2002 in Shanghai, 15 adult ICU mortality was as high as 68.5% of ARDS. ALI / ARDS is the basic pathophysiological changes a variety of inflammatory cells (macrophages, neutrophils and lymphocytes) involved in the local inflammatory response in the lungs and (or) systemic inflammation caused by runaway alveolar capillary membrane damage, increased permeability due to protein-rich non-cardiogenic pulmonary edema. Because lung water content increased pulmonary edema, pulmonary edema, pulmonary surfactant layer causes damage and reduces lung compliance; alveolar edema increased diffusion distance, reducing the bulk area and the subsequent formation of hyaline membrane caused by diffuse alveolar barrier; pulmonary vascular spasms and increased pulmonary thrombosis tiny ventilation / perfusion imbalance, resulting in severe hypoxemia. In severe cases, respiratory machine fatigue, reduced ventilation, causing Ⅱ respiratory failure. Pulmonary vascular spasm and pulmonary thrombosis can cause slight pulmonary hypertension. Pulmonary edema in ALI / ARDS pathophysiology plays an important role. ALI / ARDS early pathological features of pulmonary capillary endothelial cells and alveolar epithelial cell barrier permeability, alveolar and interstitial pulmonary edema fluid accumulation of a large number of which are rich in protein and neutrophils based multi- kinds of inflammatory cells. So ALI / ARDS patients with early inflammatory treatment, while if timely mitigation, even cure pulmonary edema, help reverse its pathophysiologic processes and improve prognosis. Many clinical studies have shown that alveolar fluid transfer function in normal maintenance can reduce mortality in patients with ALI. Alveolar liquid active absorption mechanism found previously only Starling mechanism to explain that, due to the presence of alveolar external hydrostatic pressure and osmotic pressure difference caused by absorption of water from the alveoli. Since Matthay et al found that the alveolar liquid active transport mechanism for better treatment of pulmonary edema may provide a new approach. Now that the active reabsorption of pulmonary edema is: Na alveolar epithelial cells (including type Ⅰ alveolar epithelial cells and alveolar type Ⅱ epithelial cells) apical membrane of the epithelial sodium channel (ENaC) re-absorbed into the cytoplasm, then by its basement membrane side Na , K -ATPase pump lung interstitium, Cl - alveolar epithelial cells via CFTR, K through K Channel transcellular transport, thereby forming the osmotic pressure difference across the alveolar epithelium, the alveolar water through simple diffusion or alveolar epithelial membrane water channel into the lung interstitium. Where ENaC and Na , K -ATPase are two important aspects and regulatory sites. Alveolar fluid has been found to regulate a variety of active transport mechanisms: CAMP-mediated signaling pathways, dopaminergic pathways, adenosine pathway, hormone pathway, growth factor pathways, such as serine proteases passage, wherein CAMP-mediated signaling pathway β < sub> 2 -adrenergic receptor (β 2 AR) agonists most studied and has entered many clinical trials. β 2 AR distribution in the lung airway smooth muscle and alveolar epithelium, the distribution density with increased airway series, distributed in more than 90% of the alveolar epithelium. Now that β 2 AR agonist short time through β 2 AR agonist-β 2 AR-GPCR-CAMP-PKA-cytoskeletal proteins promote intracellular transport to the plasma membrane ENaC increased alveolar epithelial membrane ENaC number; direct activation βENaC, γENaC; prolonged increased role αENaCmRNA promote αENaC expression, increasing the number of ENaC promote Na cross the alveolar epithelium forwarding promote alveolar fluid reabsorption. ENaC is composed of three protein subunits (αENaC, βENaC, γENaC) components. Distributed in the respiratory tract from the nose to the alveolar epithelial membrane. Three subunits formed in different combinations with different biological characteristics and different ways of regulating sodium ion channels. Different sodium channels are bear with αENaC, αENaC gene-deficient mice, and soon died of pulmonary respiratory distress caused too much fluid, γENaC gene deficient mice alveolar fluid clearance slowed, did not die of respiratory system concurrency disease, βENaC, γENaC gene deficient mice suffering from pseudo-aldosterone thrombocytopenia due to loss of sodium and hyperkalemia and death. Thus αENaC on alveolar fluid reabsorption is very important. To this end we produced a β 2 AR agonists increase αENaC gene expression through increased number of alveolar epithelial cells ENaC promote alveolar fluid reabsorption imagine, for we αENaC as the research object, select Classic ALI rat model of oleic acid in the lung tissue of the lung water content as an indicator of the clinical concept Chate Bu Lin in his many years of β 2 AR agonist treatment of early (1 hour) ALI rats pulmonary edema results, detecting normal rats, ALI / ARDS status rats and β 2 AR agonist group rat distal lung tissue αENaCmRNA and αENaC protein expression studies terbutaline short time of the enhanced role of oleic acid ALI rat alveolar fluid clearance mechanisms and αENaC relevance for exploring β 2 AR agonist treatment of ALI mechanism for the ALI treatment options feasible and effective way to provide reference. Materials and Methods 1, the experimental groups: by random number method 24 200 ~ 220g of SPF male SD rats (Experimental Animal Center of Southern Medical University) divided into normal group, ALI group and terbutaline treatment group were three groups , n = 8. 2, oleic acid ALI rat model of replication: The celiac artery blood gas analysis measured after injection of high purity oleic acid 0.08ml/kg, can be observed in rats shortness of breath, facial skin and mucous membrane cyanosis, 1h after intraperitoneal blood pumping, measuring blood gas analysis, and bloodletting were killed, drawing HE staining, according to the PaO 2 oxygenation index, HE staining results to determine whether the model copied successfully. 3, pulmonary edema absorption determination: terbutaline infusion therapy group after intubation sulfuric acid terbutaline aerosol 4 × 10 -4 mol / L 1ml/kg, bloodletting live to kill, take the same parts of the lung tissue wet weight was measured, and then placed inside an oven at 80 ℃ 72hs, and then said that the dry weight of the lung tissue, lung water content = lung wet weight - dry lung weight / lung wet weight × 100%. 4, the distal lung tissue total α-ENaC mRNA expression of determination: by Trizol (invitrogen TRIZOL ? Reagent) manual mention lung tissue total RNA, choose OD260/OD280 ratio of 1.7 to 1.9, pitted 1 % agarose gel electrophoresis, to obtain a bright 28S, 18S and 5S dim after three bands for eligibility criteria, selected from total RNA by RT qualified product after the reaction into the qRT-PCR reactions. ΔΔCt relative quantification using quantitative analysis of each group α-ENaCmRNA expression differences. 5, the distal lung tissue total α-ENaC protein determination: Strong with RIPA lysis buffer to extract total protein in lung tissue distal to β-actin as internal control rats in each group was measured western blot distal lung tissue relative expression of α-ENaC protein volume. 6, Statistical Methods: SPSS13.0 statistical analysis software, Microsoft Office Excel 2007 for Statistics. Sample size in each group normality test with right skewness and kurtosis to test; each group homogeneity of variance test with levene homogeneity of variance test, Pa0 2 , Pa02/FiO 2 < / sub> oleic acid for 1 h before and after comparison using paired samples t-test, and the remaining differences among the groups tested using two independent samples t test or Satterthwaite approximate t-test, P ≤ 0.05 statistically significant. Three groups were compared the line one-way ANOVA analysis of variance, P ≥ 0.1 no significant difference. Results 1, ALI rats Copy: 1.1: Clinical manifestations of rats in each group: no change in normal rats breathing (respiratory rate (R): 60 ~ 90 beats / min), no endotracheal secretions, nasal labial skin still pink; ALI rats inferior vena cava injection of oleic acid, and soon (2min) persistent shortness of breath within (R: 130 ~ 200 beats / min), mostly in 30min after sighing breathing, chest I Shield exercise, endotracheal secretions foamy red rat nasal labial skin cyanosis. 1.2: ALI group, oleic acid and oleic acid before injection 1h after injection of PaO 2 was: 12.37 ± 0.14,6.73 ± 0.10; oxygenation index: 441.87 ± 5.18,240.38 ± 3.52 two indicators of different pairing t-test P = 0.000 and 0.000 respectively, are less than 0.05. 1.3: lung histopathology: general concept: normal lung was pink, morphologically normal lung, lung edge sharpness; ALI lung Crimson nearly purple, swelling, shiny, with double lung as the most important, airway secretions; HE staining: normal lung tissue biopsy shows respiratory bronchioles, alveolar ducts, alveolar lung and other groups were normal clear, not alveolar enlargement is no red dye, alveolar wall, interstitial thin. ALI group alveolar tissue morphology such as unclear, alveolar cavity to expand, there are red dye (protein pulmonary edema), are forming transparent film; alveolar wall and interstitial significantly widened, congestion, a significant increase in neutrophils, focal lung atelectasis, necrosis. 2, terbutaline promote ALI rat alveolar fluid reabsorption effects observed: ALI rats and terbutaline treated rats PaO 2 : 6.73 ± 0.10,9.58 ± 0.12; oxygenation index: 240.38 ± 3.52,342.00 ± 4.28; lung water content: 0.855 ± 0.001,0.828 ± 0.002 by two-sample t test, P values ??were: 0.000,0.000,0.000 are less than 0.05. HE staining: ALI group of lung tissue morphology unclear, alveolar cavity to expand, there are red dye (protein pulmonary edema), are forming transparent film; alveolar wall, interstitial significantly widened, congestion, a significant increase in neutrophils, focal atelectasis. Terbutaline treatment group lung tissue morphology is acceptable interstitial widening, congestion, but mostly clear and no red dye cavity, infiltrating neutrophils was significantly reduced compared with ALI group. 3, each rat distal lung tissue α-ENaC mRNA expression differences: the normal group, ALI group and terbutaline treatment group 3 rats distal lung tissue αENaC mRNA relative expression level was not 0.97 ± 0.23, 1.06 ± 0.13 and 0.90 ± 0.19, one-way ANOVA analysis of variance were differences: P = 0.825> 0.1; each rat distal lung tissue α-ENaC protein expression differences: 3 Group αENaC protein expression was 0.217 relative ± 0.003,0.213 ± 0.002 and 0.217 ± 0.002, P = 0.344> 0.1. Conclusion 1, intravenous injection 0.08ml/kg high purity oleic acid rat model of ALI success; 2, β 2 AR agonist terbutaline can promote early ALI rat pulmonary edema reabsorption; 3, β 2 AR agonist terbutaline can promote early ALI rat pulmonary edema reabsorption than through enhanced α-ENaC gene expression achieved.
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