Mechanisms in alveolar fluid absorption

我们确定了肺泡液体吸收的机制。1.β-肾上腺素能受体激动剂对肺泡液体清除率的影响。β-1受体激动剂增加肺泡液体清除率和II型肺泡上皮细胞中cAMP水平。高浓度的特布他林刺激β受体，抑制β 2受体介导的肺泡液体清除。2.缺血再灌注肺损伤。缺血再灌注组大鼠肺泡液清除率在再灌注后1、3d增加，但在再灌注后7 d恢复至正常水平。内源性儿茶酚胺可能在增加肺泡液体清除率中起作用，但不上调钠通道mRNA。肺收缩降低肺泡液体清除率，肺泡液体清除率的降低可能是由氧自由基介导的。3.高氧或低氧对肺泡液体清除的影响。在暴露于高氧的大鼠中，β 1-激动剂和β 2-激动剂增加肺泡液体清除率。在暴露于缺氧的大鼠中，内源性去甲肾上腺素在肺泡液体清除的增加中起作用。高氧和缺氧都能保护β-肾上腺素受体的功能。4.肺切除术对肺泡液体清除的影响。肺泡液体清除率在肺切除术后一周内没有变化，但在肺切除术后2周和4周增加。肺泡灌洗液中钠通道mRNA表达增加，肺泡Ⅱ型上皮细胞增殖增加，肺泡液体清除率增加。由于许多肺部疾病都存在肺泡液体蓄积，因此研究肺泡液体清除能力的机制具有重要意义。

We determined the mechanisms in alveolar fluid absorption. 1. The effects of beta-adrenergic agonists on alveolar fluid clearance. Beta-1 agonists increased alveolar fluid clearance and cAMP levels in type II alveolar epithelial cells. High concentration of terbutal ine stimulated betal-adrenoceptors that resulted in the inhibition of beta2-receptor meditated alveolar fluid clearance. 2. Ischemia-reperfusion lung injury. Alveolar fluid clearance in rats exposed to ischemia-reperfusion increased 1 and 3 days after reperfusion, but returned to the normal levels 7 days after reperfusion. Endogenous catecholamines, but not upregulation sodium channel mRNA, might play a role in the increase of alveolar fluid clearance. Lung deflation decreased alveolar fluid clearance, and probably the decrease In alveolar fluid clearance was mediated by oxygen radicals. 3. The effects of hyperoxia or hypoxia on alveolar fluid clearance. Beta1-agonist increased-alveolar fluid clearance as well as beta2-agonists in rats exposed to hyperoxia. In rats exposed to hypoxia, endogeneus norepinephrine played a role in the increase in alveolar fluid clearance. Both hyperoxia and hypoxia preserved the function of beta-adrenoceptors. 4. The effects of pneumonectomy on alveolar fluid clearance. Alveolar fluid clearance did not change for one week after pneumonectomy but increased 2 and 4 weeks after pneumonectomy. Pneumonectomy increased the expression of sodium channel mRNA and the proliferation of type II alveolar epithelial cells and resulted in the increase in alveolar fluid clearance. It is important to study the mechanisms in alveolar fluid clearance capacity because there are many lung diseases in which fluid accumulates in the alveolar spaces.