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目的 :测定不同 p H值条件下酸性溶液对肺泡上皮屏障的损伤 ;观察特布他林对急性肺损伤大鼠肺泡液体清除功能的影响。方法 :向大鼠肺内滴注等渗酸溶液 ,机械通气 1小时后测定通过肺泡上皮屏障的双向蛋白流和肺泡液体清除率。结果 :随滴注液 p H值的降低 ,通过肺泡上皮屏障的双向蛋白流明显增加。当滴注液的 p H值由 7.0降到 1.5时 ,渗入血浆的肺泡蛋白示踪剂由 (5± 4) %增至 (33± 2 ) % ,进入肺泡腔内的血浆蛋白示踪剂由 (5± 1) %逐渐增至 (2 5± 2 ) %。当滴注液 p H≥ 3.5时 ,特布他林组 (1× 10 - 4 m ol/ L)的肺泡液体清除率较对照组高 2 1%～ 36 % (P<0 .0 5 ) ,但其作用随滴注液 p H值降低而减小 ;当 p H值≤ 2 .5时 ,特布他林对大鼠的肺泡液体清除功能无明显作用。结论 :酸溶液可损伤肺泡上皮 ,增加肺泡上皮屏障对蛋白质的通透性 ,降低肺泡上皮对液体的清除 ;特布他林通过激活肺泡上皮钠通道 ,增加肺泡液体的清除 ,进而改善急性肺损伤的病理生理变化 ,但其作用随气道 p H值降低而逐渐减小
OBJECTIVE: To determine the effect of acid solution on the alveolar epithelial barrier under different p H values. To observe the effect of terbutaline on alveolar fluid clearance in rats with acute lung injury. Methods: The rat lungs were infused with isotonic acid solution and bi-directional protein flow and alveolar fluid clearance through the alveolar epithelial barrier were measured 1 hour after mechanical ventilation. Results: Bidirectional protein flow through the alveolar epithelial barrier was significantly increased as the p H value of the infusion decreased. When the p H value of the instilled solution decreased from 7.0 to 1.5, the alveolar protein tracer infiltrating the plasma increased from (5 ± 4)% to (33 ± 2)% and the plasma protein tracer entering the alveolar space consisted of (5 ± 1)% to (25 ± 2)%. When p H ≥ 3.5, the alveolar fluid clearance in the terbutaline group (1 × 10 -4 mol / L) was 21% -36% higher than that in the control group (P <0.05) However, its effect decreased with the decrease of p H value in the instillation solution. Terbutaline had no effect on alveolar fluid clearance in rats when the p H value ≤ 2.5. CONCLUSIONS: Acid solution can damage the alveolar epithelium, increase the protein permeability of the alveolar epithelial barrier, and decrease the clearance of alveolar epithelium. Terbutaline can improve the acute lung injury by activating the alveolar epithelial sodium channel and increasing the clearance of alveolar fluid Of the pathophysiological changes, but its role with the airway p H value decreases and gradually decreased