Protective Effects Of Limb Ischemic Postconditioningon Myocardialin Rats

Objective Through the establishment of acute myocardial ischemiareperfusion model in rats, to observe the effect of myocardial ischemicpostconditioning and Limb Ischemic Postconditioning on myocardialfunction, observe biochemical markers creatine kinase (CK)， lactatedehydrogenase(LDH), the mRNA and protein expression of p70S6K andAkt in myocardium, to investigate the influence of PI3K/Akt pathway onmyocardial function in rats with Limb Ischemic Postconditioning.,and asloto investigate the superposion on cardioprotective in rats through thejointuse of Limb Ischemic Postconditioning and Ischemic Postconditioning.Methods：70rats were randomly divided into seven groups:①Sham operation group (S group)、②Ischemia/Reperfusion group(I group)、③Ischemia-Postconditioning group(p group)、④I-postC+Wortmanningroup(p-W group)、⑤Limb Ischemic Postconditioning group(L group)、⑥LI-postC+Wort(L-W group)、⑦LI-postC+I-postC group(L-P group). Fun-ction of myocardium were monitored during the procedure，the index wereLVSP、LVEDP、+dp/dtmax、-dp/dtmax.Observe creatine kinase (CK)、lactate dehydrogenase(LDH) of different groups at the end of reperfusion.The mRNAand protein expression of Akt and p70S6K in myocardium were tested by RT-PCR and immunohistochemistry.Results：1. The LVEDP level of S group was lower than other groups（P<0.05）,The LVSP、+dp/dtmax、-dp/dtmax level of S group was higherthan other groups（P <0.05）.The LVSP、+dp/dtmax、-dp/dtmax level ofP group、L group、L+P group were higher than I group、P+Wgroup、L+W group（P <0.05）,the LVEDP of P group、L group、L+Pgroup was lower than I group、P+W group、L+W group（P <0.05）. TheLVEDP、 LVSP、+dp/dtmax、-dp/dtmax level of P group、L group andL+P group had no significant differences（P>0.05）, The LVEDP、 LVSP+dp/dtmax、-dp/dtmax level of I group、P+W group and L+W group hadno significant differences（P>0.05）.2. The amount of CK、LDH: The amount of CK、LDH of S group washigher than other groups（P <0.05）. The amount of CK、LDH of P group、L group、L+P group were higher than I group、P+W group、L+W group（P <0.05）. The amount of CK、LDH of P group、L group and L+P grouphad no significant differences（P>0.05）, The amount of CK、LDH of Igroup、P+W group and L+W group had no significant difference（sP>0.05）.3. The expressions ofAkt、p70s6k protein: Akt、p70s6k protein couldexpress in each group, S group expressed the lowest. The expressions ofAkt、p70s6k protein of P group、L group、L+P group were higher than Igroup、P+W group、L+W group（P <0.05）. The expressions of Akt、p70s6k protein of P group、L group、L+P group had no significant differences（P>0.05）, The expressions ofAkt、p70s6k protein of I groupP+W group and L+W group had no significant differences（P>0.05）.4. Akt mRNA、p70s6k mRNA：the Akt mRNA、p70s6k mRNAexpressed in myocardium in each group, S group was the lowest expression.The expressions ofAkt mRNA、p70s6k mRNAof P group、 Lgroup、 L+Pgroup were higher than I group、 P+W group、 L+W group （P <0.05）.The expressions ofAkt mRNA、p70s6k mRNAof P group、 Lgroup、 L+Pgroup had no significant differences（P>0.05）, The expressions of AktmRNA、p70s6k mRNA of I group、P+W group and L+W group had nosignificant differences（P>0.05）.Con clusion：1. I-PostC can obvisely improve the impaired myocardial functioncaused by myocardial ischemia/reperfusion injury， the protective effectsof I-Post on myocardial myocardial systolic and diastolic function may berelated to the activation of PI3-Akt signaling pathways.2. LI-postC can significantly protect the myocardial function, andexert similar protective effects on myocardial to I-Post.And theprotective effects of on myocardial systolic and diastolic function causedby I/R injury may be related to the activation of PI3-Akt signaling pathways.3. I-PoctC and LI-postC take together can not stronger theCardioprotection effects of schemia/Reperfusion injury.