Abstract: AIM: To study the effect and mechanism of H₂S in rats with pulmonary edema induced by oleic acid.METHODS: Thirty two rats were randomly divided into four groups: control group (CG) ,the rats ware injected with normal saline 0.2 mL/100 g intravenously followed by intravenous of normal saline 7 uL/100 g. Model group (MG) ,the rats were injected normal saline 0.2 mL/100 g intravenously, then injected with oleic acid 7 uL /100 g. Prevention group(PG), the rats were injected with NaHS 3.4mg/kg, then injected by equal amount of oleic acid intravenously and NaHS group(SG) ,the rats were injected with NaHS 3.4 mg/kg, then injected normal saline 7 uL /100 g intravenously. After 40 min, the rats were killed. blood and lung were got for analyzing the level of MDA and the activity of SOD, observing lung pathologic gross and pathologic changes, calculating wet and dry weight ratioRESULTS: Compared with the CG group,flaky bleeding was emerged in the lung surface,focal consolidation and infarction and subcapsular congestion seriously in MG group.Oleic acid increased the thickness of alveolar septal, damaged the alveolar wall, and made alveoli full of pink secretion and round bubbles. Moreover, W/D and the level of MDA in blood plasma and lung tissue in MG group were increased obviously compared with those in CG group. But the activity of SOD decreased significantly. Lung surface only emerged flaky bleeding on the lower lung fields, slight interstitial thickening, minority alveolar exited pink secretion in PG group. W/D and the level of MDA in plasma and lung tissue in PG group were decreased obviously compared with those in MG group. The activity of SOD was increased significantly in PG group. Meanwhile, indicators of SG group have no significant differences.CONCLUSION: H₂S has the effects of alleviating the lung injury, decreasing plasma exudation, and mitigating pulmonary edema. The mechanism may be correlation with enhancing the antioxidation, alleviating oxidative damage of lung tissue and lowering blood pressure.

Key words: H₂S, oleic acid, pulmonary edema