Abstract： Objective To investigate the effects of hydrogen sulfide on sepsis-induced cardiac dysfunction in rats.Methods Male SD rats were randomly ( random number) divided into 4 groups:control group ( Ⅰ group),sepsis group ( Ⅱ group),sepsis + NaHS group (Ⅲ group),sepsis + PAG group (Ⅳ group). Cecal ligation and puncture technique was used in Ⅱ, Ⅲ, Ⅳ group. Hemodynamic was observed,and H2S synthesis,CSE (cystathionine-r-lyase) mRNA,MPO activity and the level of TNF-α,IL-1β were determined.The morphological changes and infiltration of inflammatory cells in myocardium were also observed.Results Compared with Ⅰ group,H2S synthesis,the levels of TNF-α,IL-1 β,the activity of MPO increased ( P ＜ 0.05 or P ＜ 0.01 ),and the expression of CSE-mRNA increased,and blood pressure of rats decreased significantly in Ⅱ group.Compared with Ⅱ group,H2S synthesis,the levels of TNF-α,IL-1β and the activity of MPO increased (P ＜ 0.05),the expression of CSE mRNA did not change noticeably ( P ＞ 0.05),and blood pressure of rats decreased more significantly in Ⅲ group.Compared with Ⅱ group, H2S level decreased,the levels of TNF-α,IL-1β and the activity of MPO decreased significantly,the expression of CSE mRNA decreased and blood pressure of rats decreased in Ⅵ group (P ＜0.05).Histopathological changes of myocardium were aggravated in the following severity order: Ⅰ ＜ Ⅳ ＜＜ Ⅲ.Conclusions CSE/H2S system of the myocardium was upregulated in sepsis rats.Hydrogen sulfide could raise the levels of MPO,TNF-α,IL-1β,aggravating myocardial injury. Contrarily,the inhibitor of H2S could counteract it.