Changes in liquid clearance of alveolar epithelium after oleic acid-induced acute lung injury in rats.
OBJECTIVE
Impaired active fluid transport of alveolar epithelium may involve in the pathogenesis and resolution of alveolar edema. The objective of this study was to explore the changes in alveolar epithelial liquid clearance during lung edema following acute lung injury induced by oleic acid.


METHODS
Forty-eight Wistar rats were randomly divided into six groups, i.e., injured, amiloride, ouabain, amiloride plus ouabain and terbutaline groups. Twenty-four hours after the induction of acute lung injury by intravenous oleic acid (0.25 ml/kg), 5% albumin solution with 1.5 microCi (125)I-labeled albumin (5 ml/kg) was delivered into both lungs via trachea. Alveolar liquid clearance (ALC), extravascular lung water (EVLW) content and arterial blood gases were measured one hour thereafter.


RESULTS
At 24 h after the infusion of oleic acid, the rats developed pulmonary edema and severe hypoxemia, with EVLW increased by 47.9% and ALC decreased by 49.2%. Addition of either 2x10(-3) M amiloride or 5x10(-4) M ouabain to the instillation further reduced ALC and increased EVLW. ALC increased by approximately 63.7% and EVLW decreased by 46.9% with improved hypoxemia in the Terbutaline (10(-4) M) group, compared those in injured rats. A significant negative correlation was found between the increment of EVLW and the reduction of ALC.


CONCLUSIONS
Active fluid transport of alveolar epithelium might play a role in the pathogenesis of lung edema in acute lung injury.
Department of Anesthesiology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China. xqtaojun@hotmail.com
Jun
J
Tao
Tian-de
TD
Yang
Xiang-rui
XR
Chen
He
H
Huang
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D004848:Epithelium / Q000378:metabolism; D019301:Oleic Acid / Q000009:adverse effects; D011650:Pulmonary Alveoli / Q000378:metabolism*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012128:Respiratory Distress Syndrome / Q000139:chemically induced / Q000378:metabolism*; D013726:Terbutaline / Q000494:pharmacology
D000318:Adrenergic beta-Agonists; D019301:Oleic Acid; D013726:Terbutaline