Objective      To determine the intervention effect of taurine on oleic acid-induced acute lung injury (ALI) in rats and investigate its possible mechanisms

especially the role of synthesis and secretion of urotensin Ⅱ (UⅡ) and intermedin (IMD).       Methods       A total of 54 SD rats

at an age of 9 weeks

weighting 280 to 310 g

were randomly divided into 3

groups

control (n=6)

the ALI group (n=24) and the taurine treatment group (n=24). Rat models of ALI were established by tail vein injection of 0.15 mL/kg oleic acid. Taurine solution was given intraperitoneally at a dose of 20 mg/mL

0.1 mL/kg for 3 consecutive days before oleic acid injection. Blood sample of 2 mL were drawn from the arteries at 0

6

12

and 24 h after oleic acid injection

while   bronchioalveolar lavage fluid   (BALF) was taken at the same time points to measure arterial partial pressure oxygen [

p

(O

2

)

]

. The plasma and BALF contents of UⅡ and IMD

and lung wet-to-dry ratio (W/D) were measured and counted. Immunohistochemical assay was used to detect the expression of UⅡ and IMD in lung tissues. Electron microscopy was used to observe the ultrastructure of lung tissues.       Results    

p

(O

2

) was significantly higher in the treatment group than in the model group at 6

12 and 24 h (

P

0.05). The W/D ratio was obviously higher in the model group than in the treatment group at 0 and 6 h (

P

0.05). Plasma content of UⅡ was obviously higher in the model group than in the treatment group  at 24 h (

P

0.05). There were significant differences in BALF content of UⅡ between model group and treatment group at 0 and 6 h (

P

0.05). It was remarkably higher in the treatment group than in the model group at 0 h (

P

0.05)

while higher in the model group than in the treatment group  at 6 h (

P

0.05). But for plasma content of IMD

it was obviously higher in the treatment group than in the model group at 0 h (

P

0.05). Electron microscopy displayed that the injury of lung tissue was milder in the treatment group than the other groups. Immunohistochemical assay showed there were positive expression of UⅡ and IMD in the bronchial epithelial cells

smooth muscle cells

and pulmonary vascular endothelial cells in the 3 groups

and no significant difference was seen between the model group and treatment group. Electron microscopy indicated

the injury was significantly milder in the treatment group than in the model group

with intact basement membrane and without obvious collagen hyperplasia.       Conclusion      Taurine alleviates the lung injury induced by oleic acid

which might be due to its inhibiting the expression of UⅡ and protecting the capillary basement membrane to reduce plasma protein exudation.