Abstract: OBJECTIVE: To investigate the effect of Sanao Tang(SAT) on urine volume and the expression of aquaporin-2(AQP2) in rats with lung dysfunction induced by passive smoking and lipopolysaccharide.METHODS: Totally 45 healthy Specific pathogen Free Wistar Rats were randomized into 3 groups:normal control group, model group and SAT group.A rat model of respiratory dysfunction induced by exposure to cigarette smoking and lipopolysaccharide(LPS). Lavage of decoction of the Chinese medicine was performed for rats in the SAT group. Anires 2005 System was used to analyze the pulmonary function. Urine of rats was collected through metabolism cage method. Enzyme-linked immunosorbent assay(ELISA) was used to determine content of antidiuretic hormone(ADH), angiotensin Ⅱ(AngⅡ), atrial natriuretic factor(ANP), endothelin 1(ET-1), nitric oxide(NO) and prostaglandin E2(PGE2) in serum, lung and kidney. The expression of AQP2 in rat renal tissue was determined with real-time fluorescence quantitative PCR(RT-PCR).RESULTS:(a) In comparison with the normal control, It was found that enforced vital capacity(FVC),1-second forced expiratory volume/forced vital capacity%(FEV1/FVC%), 24 h urine volume content of NO and PGE2 were decreased, while AQP2 m RNA level and content of ADH, Agn Ⅱ, ANP and ET-1were increased in the model group with statistical significance(P < 0.05).(b) In comparison with the model group, It was found that FVC, FEV1, FEV1/FVC%, 24 h urine volume, content of PGE2 and NO decreased, while AQP2 m RNA level, content of ANP,ADH and AngⅡ decreased in the SAT group with statistical significance(P < 0.05).CONCLUSION: SAT might effectively regulate the urine volume in the modeled rats; ADH, Ang Ⅱ,ANP, ET-1, NO and PGE2 might play an important role in the regulation on urine volume by lungs.This might be the mechanisms underpinning the function of lung governing water passage in terms of the theory of Traditional Chinese Medicine.

Key words: Regulation of water passage, Lung Qi, Urine, Aquaporin 2