Abstract： Objective To study the protective effects on isolated rabbit heart preservation by H2S and its mechanism.Methods New Zealand white rabbits (2.0～2.5 kg, n=40) were randomly divided into 5 groups (n=8 in each group),and their hearts were preserved with K-H (control group),NaHS,glibenclamide (G1i),NariS+Gli,ST.Thomas (STH) solution respectively for 6 h.The isolated hearts were perfused in the Langendorff rat mode for functional evaluation before and after preservation.After reperfusion,some indexes were measured,including the left ventricular function recovery as percentage (dp/dtmax),contents of adenosine triphosphate and wet weights in myocardium,and uhrastructural changes in myocardium were also observed by electron microscopy.Results Hearts were preserved with solution respectively for 6 h. NaHS group offered the fastest dp/dtmax,and had the highest ATP content of myoeardium among the 5 groups.There were no significant differences in releases of dp/dtmax and ATP level of myoeardium between NaHS and STH group (P＞0.05),but the differences were significant between NaHS group and K-H,Gli,NaHS+ Gli groups (P＜0.05).The impairment of the left vemricle function and ultrastructure in NaHS,STH groups was mild,while that in K-H,Gli,NaHS+Gli groups was severe.Conclusions NaHSsolution can protect rabbit heart for 6 h effectively.The recovery of heart function and the protection of structure by H2S are similar to that by ST.Thomas solution.The protective effects by H2S may be mediated by ATp-sensitive K+ channels.