Protection Of Hydrogen Sulfide Delayed Preconditioning On Myocardial Ischemia-reperfusion Injury In Rats

Objectives:Observe the protective effect of hydrogen sulfide delayed preconditioning on myocardial ischemia-reperfusion injury in rats.Methods:1.50 Sprague-Dawley adult male rats were randomly divided into 5 groups:Sham group:we exposed heart by surgery and isolated left anterior descending(LAD) coronary artery, but not blocked LAD for 150 minutes; IR group:for ischemia-reperfusion group, we blocked LAD for 30 min and then primed for 2h; HS group:for hydrogen sulfide delayed preconditioning group, we injected sodium hydrosulfide 50μg/kg via vein, after 24h, dealed same with IR group; HA group:for hydrogen sulfide delayed preconditioning and MPTP opener(atractylode, ATR) group, we injected ATR 15min before blocking LAD via vein, other steps dealed same with HS group; HD group:for hydrogen sulfide delayed preconditioning and mitoK(ATP) blocker (5-hydroxydecanoate,5-HD) group, we injected 5-HD 15min before blocking LAD via vein, other steps dealed same with HS group.We measured left ventricular hemodynamics; measured infarct region by Evan's blue and triphenyl tetrazolium chloride (TTC) staining; observed myocardial ultrastructure under the electron microscope; detected serum CK-MB and cTnT levels; detected expression of Bcl-2 and Bax protein with Western Blotting analysis.Results:1. Comparison of hemodynamics:HR and left ventricular pressure had no significant difference before ischemia in each group(all P>0.05). During I/R, compared with Sham group, HR,LVESP,±dp/dt. max and LO all decreased and LVEDP increased in IR,HS,HA and HD group, moreover, there was significant difference(all P<0.05); compared with IR group, HR,LVESP,±dp/dt.max and LO all increased and LVE-DP decreased in HS group, moreover, there was significant differen-ce(all P<0.05), but there was no significant difference separately in HA and HD group(P>0.05).2. Comparison of area of necrosis:compared with IR group, area of necrosis decreased in HS group, moreover, there was significant differ-ence(P<0.05), but there was no significant difference separately in HA and HD group (P>0.05).3. TEM:compared with IR group, damage of myocardial ultrastruc-ture was decreased significantly in HS group, but there was no signific-ant difference in HA, HD group.4. Serum CK-MB and cTnT levels:compared with Sham group, CK-MB and cTnT increased in IR,HS,HA and HD group, moreover, there was significant difference(P<0.05); compared with IR group, CK-MB and cTnT decreased in HS group, moreover, there was significant differ-ence(P<0.05), but there was no significant difference separately in HA and HD group(P>0.05).5. Bcl-2/Bax protein expression:compared with Sham group, Bcl-2 protein decreased and Bax protein increased in IR, HS, HA and HD groups, moreover, there was significant difference(P<0.05); compared with IR group, Bcl-2 protein increased and Bax protein decreased in HS group, moreover, there was significant difference(P<0.05), but there was no significant difference separately in HA and HD group(P> 0.05).Conclusions:1. Hydrogen sulfide delayed preconditioning can improve myocardial function of relaxation and contraction, reduce area of necrosis and releasing of enzyme to protect cardiac function.2. Hydrogen sulfide can inhibit cardiomyocyte apoptosis through regulating Bcl-2 and Bax protein expression.3. Hydrogen sulfide can reduce the oxidative stress response to protect myocardium by regulating MPTP and mitoK(ATP) opening or closing.