| Objective: The apoptosis is connected closely with the Myocardial ischemic reperfusion injury,ischemic preconditioning and ischemic postconditioning. The protective machanism is a investigative and popular subject about the ischemic postconditioning,especially the pharmacal postconditioning to Myocardial ischemic reperfusion injury.The aim of this experiment is to discuss the protective mechanisms about ischemic postconditioning and pharmacal postconditioning for ischemia reperfusion injury.Methods: A New-Zealand rabbit model of heart warm I-R injury was establshed. New-Zealand rabbit was anesthetized with 30% urethane 3ml/kg by being injected from ear-edge vein after abrosiaing 12h. Rabbit was fixed on the operating-table.Sterilizing the neck of rabbite,incision of trachea,trachea cannula,being connected with DH-140 model animal breathing machchine(breathing frequency40/min,tide volume30ml,fraction of inspired oxygen100%).Opening chest through 3-4 ribs in left,bracing chest with little open-organ,unfolding pericardiumto reveal cordis,observing heartbeat and color,then making sure of its normal.Ligated line with cannula to reduse injury of vessel wall was through under left auricular appendage,to ligate left anterior descending coronary artery.Electrocardiogram limb lead was embeded in subcutaneouly to record the change of ST-stage.It will be blest if the ST stage of synchronization electrocardiogram criteria II lead rise,QRS highten and cyanoderma happened in left ventricle under ligature line.Abstracting right femoral vein was ready to draw blood to be checked. Twenty-four healthy New-Zealand rabbites(2O00-25O0g) were devided into three groops randomly. I/R group:the hearts were subjected to 40 min global ischemia followed by 60 min reperfusion;ischemic postconditioning group:the hearts underwent 3 cycles of alternate 10s isehemia and 10s reperfusion immediately after 40 min isehemia and before 59 min reperfusion and Edravone postconditioning group:the hearts were repefused immediately after 40min ischemia with Edravone 3mg/kg for 10 min followed by 50min reperfusion.CK-MB leakage into the coronary effluent was measured at 5 min before ischemia 30min and 60 min of reperfusion.Myocardial SOD activity and MDA and ATP contents were determined at the end of reperfusion.Apoptosis Index of the cell was measured with the way of TUNEL and Bcl-2 was measured with flow cytometry and indirect immunofluorescence.Myocardium ultramicrostructure was observed with the eletronic microscope. Cell apoptosis was measured by the way of TUNEL.Results:(1)The test showed : the CK-MB activity of 5 min before ischemia, IR groop(35.12±5.23), HCL groop(35.20±5.28), YPC groop(35.24±5.43);30 min after reperfusion, IR groop(122.32±10.14), HCL groop(65.34±6.28), YPC groop(67.26±7.34); at the end of reperfusion , IR groop (135.25±9.26), HCL groop(69.67±6.78), YPC groop(72.85±6.24). the CK-MB activity of three groops,at 30 min after reperfusion and at the end of reperfusion,were higher than at 5 min before ischemia(P<0.05); The CK-MB activity had no significant difference at 5 min before ischemia among three groops(P>0.05);The CK-MB activity decreased at 30 min after reperfusion and at the end of reperfusion,in YPC groop and HCL groop,compared with IR groop(P<0.05); The CK-MB activity had no significant difference between YPC groop and HCL groop(P>0.05).(2) At the end of reperfusion, the MDA content, IR groop(65.32±12.28),HCL groop(52.11±11.23), YPC groop(54.32±10.33); the SOD activity, IR groop(57.24±10.38), HCL groop(71.35±11.87), YPC groop(69.53±10.67); ATP content , IR groop(3.00±0.42), HCL groop(4.21±0.53), YPC groop(4.37±0.64). the SOD activity and ATP content were higher in YPC groop and HCL groop compared with IR groop, at the end of reperfusion(P<0.05);The MDA content was lower in YPC groop and HCL groop compared with IR groop, at the end of reperfusion(P<0.05). The SOD activity , ATP content and MDA content had no significant difference between YPC groop and HCL groop(P>0.05).(3) At the end of reperfusion, the Bcl-2 content, IR groop(FI=0.70±0.06), HCL groop(FI=0.98±0.04), YPC groop(FI=0.97±0.07); the Bax content, IR groop(FI=1.65±0.15), HCL groop(FI=1.27±0.14), YPC groop(FI=1.21±0.14); the myocardial apoptosis index, IR groop(19.75±1.81)%, HCL groop(10.46±0.91)%, YPC groop(9.68±0.59)%. The Bcl-2 content was higher but the Bax content and the myocardial apoptosis index were lower in YPC groop and HCL groop compared with IR groop, at the end of reperfusion(P<0.05). The Bcl-2 content , the Bax content and the myocardial apoptosis index had no significant difference between YPC groop and HCL groop(P>0.05).(4)Lots of myocardial myofilament was dissolved and Z-line was broken and cytochondriome was swelling or disaggregation in I/R group.But, cytochondriome was swelling or disaggregation littlely in the 2 postconditioning groups.(5)Masccline cell dyed by the way of TUNEL showed:cell were sperical, crimpled, karyopycnosis, dyed deeply and caryon was dyed deeply,less in cytolymph. masccline cell dyed by the way of TUNEL were more in IR groop than in 2 postconditioning groops.but,there was no significant diference in HCL and YPC groops.Conclusions:(1)Edravone postconditioning is as effective as ischemic postconditioning in the protection of myocardium against I/R injury in rabbit through decreasing oxygen free radicals and increasing antioxidant activity and decreasing energy comumption of myocardial cells.(2)Edravone postconditioning is as effective as ischemic postconditioning in the protection of myocardium against I / R injury in rabbit through increasing Bcl-2 protein,decreasing Bax protein to reduse apoptosis.
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