OBJECTIVETo observe the changes of pulmonary surfactant (PS) in rats with acute lung injury(ALI) induced by lipopolysaccharide (LPS) and to explore the effects of hydrogen sulfide (H2S) on PS.

METHODSFourty- eight male rats were randomly divided into six groups (n = 8). They were control group, LPS group, LPS+ NaHS low, middle, high dose groups and LPS+ PPG group. Saline was administrated in Control group. LPS was administrated in LPS group. In LPS + NaHS low, middle, high dose groups or LPS + PPG group, sodium hydrosulfide (NaHS) of different doses or DL-propargylglycine (PPG) were respectively administrated when the rats were administrated of LPS after 3 hours. All the rats were killed at 6 hours after administration of Saline or LPS. The morphological changes of alveolar epithelial type II cells (AEC-II) were respectively observed by transmission electron microscopes. The content of H2S in plasma and activity of cystathionine-gamma-lyase (CSE) in lung tissues were respectively detected. The contents of total protein (TP) and total phospholipids (TPL) in bronchoalveolar lavage fluid (BLAF) were respectively measured. The pulmonary surfactant protein A (SP-A), surfactant protein B (SP-B) and surfactant protein-C (SP-C) mRNA expressions in lung tissues were analysed.

RESULTS(1) Compared with control group, the content of H2S in plasma, activity of CSE, content of TPL, and SP-A, SP-B and SP-C mRNA expressions were respectively decreased in LPS group (P < 0.05 or P < 0.01). But the content of TP was increased in LPS group (P < 0.01); (2) Compared with LPS group, the content of H2S, activity of CSE and SP-A mRNA expression were significantly increased in LPS + NaHS low, middle and high dose groups (P < 0.05). The SP-B mRNA expression and content of TPL were significantly increased in LPS + NaHS Middle and High dose groups (P < 0.05). The content of TP was decreased in LPS + NaHS High dose group (P < 0.05). The SP-C mRNA expression was not altered in LPS+ NaHS low, middle and high dose groups (P > 0.05); (3) Compared with LPS group, the content of H2S, activity of CSE, content of TPL, and SP-A, SP-B and SP-C mRNA expressions were respectively decreased, but content of TP was increased in LPS + PPG group (P < 0.05).

CONCUSIONThe decrease of PS is the important physiopathologic process of ALI induced by LPS. Exogenously applied H2S could attenuate the process of ALI that possibly because H2S could adjust the compose and secretion of PS.