Mechanisms in alveolar fluid absorption

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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.