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Objective To observe the natural fasting gastric juice (pH = 2.3) inhalation acute lung injury in rats and to explore its possible mechanism. 27 male Sprague-Dawley rats were randomly divided into three groups: A group (n = 9) was the control group; hydrochloride group B (n = 9) group (pH = 2.3); C group (n = 9) human nature fasting gastric juice group (pH = 2.3). Three groups of rats were anesthetized, A group only tracheotomy and femoral artery and vein puncture surgery, B group, C group are 0.8ml/kg capacity transtracheal catheter hydrochloric acid or gastric juice into the rat lung monitoring basic state inhalation after 30min, 1h, 2h, 3h and 4h PetCO2 (end-breathing carbon dioxide partial pressure) and RR (respiratory rate), hour after inhalation of measurement 4h plasma IL-8 content and inhalation 4h arterial blood gas. To 4h animals were sacrificed, and the determination of the right middle lobe lung wet-dry weight ratio (W / D), observation of the right lung histopathological changes, the line left lung lavage lavage fluid (BALF) was measured in lung permeability index (BLAF total protein / serum protein), and the determination of the total number of leukocytes (WBC total) in BALF polymorphonuclear neutrophils (PMN) / white blood cell (WBC), myeloperoxidase (MPO) and IL-8 levels. Results (1) B group, C group inhaled RR faster (P lt; 0.05), PetCO2 changes at each time point, the difference was not statistically significant. (2) group B and group C PaO2 decreased 4h after inhalation, and group C than in group B decreased significantly (P lt; 0.05). (3) compared with group A, group B, group C lung W / D and lavage fluid protein content increased (P lt; 0.05) the C group lung permeability index was significantly increased (P lt; 0.05). (4) C group 1 h after inhalation, 4h plasma, and inhalation after 4h BALF IL-8 levels were higher than the A group and B group (P lt; 0.05). Compared with group A, group B, C group BALF WBC count increased; PMN / WBC and MPO activity in group C than in group A and group B (P lt; 0.05). (5) of gastric juice in BALF PMN / WBC and BALF and 4h plasma IL-8 levels in BALF MPO activity coefficients were 0.756,0.796,0.726 (P lt; 0.05). (6) was observed under an optical microscope lung tissue visible group A, no apparent damage or injury is minor, the C group, injury is the most serious, visible destruction of alveolar walls, diffuse congestion and edema, pulmonary interstitial and alveolar edema, widening of the alveolar septa, most alveolar collapse, intrapulmonary polymorphonuclear neutrophils (Polymorphonuclear neu-trophil leukocytes, PMN) infiltration. Group B lung tissue injury is lighter than the C group. (7) The transmission electron microscope visible discontinuity of group C, pulmonary capillary basement membrane, capillary endothelial cell swelling, endothelial cell gap widened, type Ⅱ alveolar epithelial cell microvilli extent of the damage is serious, the B group of lung tissue injury between Group A and group C between. More serious the conclusion naturally fasting gastric juice (pH = 2.3) inhalation lung injury caused by inhaled than simply hydrochloric acid (pH = 2.3), the degree of lung injury. Gastric juice aspiration lung injury, IL-8, of PMN and MPO involved in the inflammatory response, and increased expression levels of IL-8 and MPO and the role of the PMN, this inflammatory response is stronger than pure hydrochloric acid inhalation.
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