Abstract: AIM: To investigate the levels of endogenous hydrogen sulfide(H₂S)and cystathionine-γ-lyase(CSE)mRNA of acute asthma, and to explore the functions of H2S and CSE in mechanism of asthma exacerbation.METHODS: Thirty male SD rats were randomly divided into three groups, named asthma group,control group and dexamethasone treated group.The contents of H₂S were detected in the blood plasma by spectrophotometry.The levels of CSE mRNA in the lung tissues were detected by RT-PCR.RESULTS: The contents of H₂S in plasma of asthma group(61±16)μmol/L were significantly decreased than those in control group[(84±15)μmol/L, P<0.01].But there were nosignificance between dexamethasone treated group[(73±16)μmol/L] and control group(P>0.05), and there were nonsignificance between dexamethasone treated group and asthma group either(P>0.05).Levels of CSE mRNA in the lung tissues of asthma group(0.14±0.02 vs 0.33±0.04)were significantly decreased than those in control group (0.46±0.05)(P<0.01).And in dexamethasone treated group(0.33±0.04), levels of CSE mRNA in the lung tissues were significantly increased than those in asthma group(P<0.01), but were significantly decreased than those in control group(P<0.01).There were significantly positive correlation between contents of H₂S in the blood plasma and levels of CSE mRNA in the lung tissues(n=30, r=0.504, P<0.01).CONCLUSION: The contents of H₂S in the blood plasma and levels of CSE mRNA in the lung tissues are decreased in asthmatic rats.They possibly participate in the inflammation process of asthma.Dexamethasone reducing the airway inflammation of asthma is possibly in part to the system of H₂S CSE.

Key words: asthma, rat, hydrogen sulfide, cystathionine-γ-lyase, dexamethasone