| Background: Acute myocardial infarction is acute coronary artery,persistent ischemia and hypoxia caused by myocardial necrosis.Clinically,there are more severe and persistent posterior sternal pain,rest and nitrate drugs which can not be completely resolved,accompanied by increased serum myocardial enzymes and progressive ECG changes can be complicated by arrhythmia,shock or heart failure.Acute myocardial infarction serious harm to human life and health has become the world's most common diseases.Early recovery of coronary blood flow is the key to treatment,but there will be a series of reperfusion injury.Although pretreatment can significantly reduce reperfusion injury,but it can not predict the clinical ischemia so that it is not well implemented,thus limiting the application of pretreatment.In 2005,Staat et al.[1] firstly applied ischemic postconditioning to the clinical setting,reducing the infarct size by 36% compared with the control group.Our laboratory has confirmed that ischemic postconditioning can effectively reduce reperfusion arrhythmia,improve cardiac function and reduce myocardial infarction area [2].Mechanical post-treatment can play a protective role in reperfusion injury,but at the same time there may be vascular wall injury,plaque loss,embolism and other risks.Pharmacology postconditioning is a long time after ischemia,before reperfusion or reperfusion within a few minutes of medication,through drug intervention to reduce organ ischemia-reperfusion injury.It can avoid the damage caused by mechanical post-treatment,clinical implementation.Currently there are a variety of drug post-treatment drugs which are nitroglycerin,diltiazem,adenosine,nicorandil and so on.These four drugs using different mechanisms of action of myocardial ischemia and reperfusion injury have played a protective role,but the difference between the four drugs for the treatment has not been studied.This paper aims to study these four drugs and to explore whether mitochondrial ALDH2 is involved in the mechanism of myocardial ischemia / reperfusion injury in rats,and to provide a theoretical basis for the clinical application of the combination therapy alone or in combination.Objective: 1.To observe the effects of nitroglycerin,diltiazem,adenosine and nicorandil on left ventricular function(LVDP,± dp/dtmax),RA,myocardial infarct size and the effect of area and the contrast between the drugs.2.To investigate the effects of four drugs on the expression of ALDH2 in rat ventricular myocardium after myocardial ischemia/reperfusion injury,and to investigate whether ALDH2 is involved in the mechanism of drug action.Methods 1.Comparison of postconditioning effects on myocardial ischemia / reperfusion injury in isolated rat: Nitroglycerin(10-8mol/L),Diltiazem(5?mol/L),Nicorandil(200?mol/L)and Adenosine(100?mol / L)were added into Krebs-Henseleit(KH)Stir well.66 male Wistar rats were randomly divided into six groups: normal group(N group),ischemia reperfusion group(IR group),nitroglycerin + ischemia reperfusion group,diltiazem + ischemia reperfusion group,Ischemia + reperfusion group,adenosine + ischemia reperfusion group(n=11 in each group).Langendorff isolated heart perfusion test system and BL-420 S biological function test system were used.The rats in IR group were perfused with normal solution for 30 min,then ligated for 30 min,followed by reperfusion for 90 min.After reperfusion,nitroglycerin,diltiazem,nicorandil and adenosine for 15 min,then followed by perfusion with normal fluid for 75 min.With 3-0 medical suture 3/8 bending needle in the left atrial appendage 2mm below the root surface through the myocardial surface in the pulmonary artery conical needle [3] hook around the coronary artery anterior descending branch,the needle depth of 0.5-1mm,Width of 2-3mm [4].After 30 min of stable perfusion,the balloon was inserted into the balloon and the balloon was ligated.The balloon was pressurized to 6 k Pa.At this time we would see the ECG ST-segment elevation,left ventricular heart surface began to lose the original ruddy luster and gray,left ventricular systolic activity weakened and left ventricular pressure by half.The phenomena can determine the exact location of ligation [5]:Myocardial infarction model was established.30 min after the released the balloon ligation and opened the ligation line,reperfusion 1.5h.1% Evans-blue 2ml was retrogradely injected into the heart of aortic root,rinsed with PBS liquid and then quickly placed in 1% TTC solution to re-staining,distinguish between normal(Dark blue),ischemic non-infarcted area(red)and infarcted area(gray-white).TTC staining of cardiac tissue could not be used for follow-up of molecular biology [6],tissue specimens separately.Left ventricular function(LVDP),maximal rise/fall rate of left ventricular pressure(±dp/dtmax),reperfusion arrhythmia(RA)and myocardial infarct size were recorded and analyzed.2.The effect of drug postconditioning on the expression of ALDH2 in rat ventricular myocardium after myocardial ischemia / reperfusion injury.The animal experiment group was the same as the first part,and the left apex tissue of the left ventricle was taken after perfusion.The tissue used for Real time RT-PCR was stored in liquid nitrogen,and the tissue used for Western blot was stored in a refrigerator at-80 ° C.Real-time fluorescence RT-PCR was used to detect the expression of ALDH2 gene.Western Blot using polyacrylamide gel electrophoresis,the test object is the protein through the substrate color or autoradiography to detect electrophoretic separation of specific target gene expression of mitochondrial ALDH2 protein expression.Results:1.1 LVDP in I-R group was lower than the other groups after 30 min and 45 min reperfusion(P<0.05).In the drug post-conditioning groups:Diltiazem in 30 min reperfusion LVDP [(92.68 ± 5.09)mm Hg vs(84.26 ± 3.02)mm Hg vs(83.35 ± 2.88)mm Hg] and the nicorandil group [(88.95 ± 1.75)mm Hg](84.36 ± 3.02)mm Hg vs(83.35 ± 2.88)mm Hg] and diltiazem group in 45 min reperfusion LVDP [(90.39 ± 4.29)mm Hg vs(82.09 ± 4.24)mm Hg vs 80.98 ± 3.89 mm Hg] and nicorandil group[(86.13 ± 2.38)mm Hg vs(82.09 ± 4.24)mm Hg vs(80.98 ± 3.89)mm Hg] were higher than nitroglycerin and adenosine groups.Diltiazem group was higher than nicorandil group,and the difference was statistically significant(all P <0.05).But the difference in nitroglycerin group and adenosine group was not statistically significant(P>0.05).1.2 ± dp / dtmax in I-R group was lower than the other groups after 30 min and 45 min reperfusion(P<0.05).± dp / dtmax in diltiazem group and nicorandil group were significantly higher than those in nitroglycerin group and adenosine group at 30 minand 45 min after reperfusion.Diltiazem group was higher than nicorandil group,and the difference was significant(P<0.05).But there was no significant difference between nitroglycerin group and adenosine group(P> 0.05).2.Comparison of RA score: IR group score [5(3,6),57.36] was significantly higher than the drug post-conditioning t groups: nicorandil group [1(1,3),22.05],diltiazem group [3(1,4),34.77],nitroglycerin group [4(1,4),45.41] and adenosine group [2(1,3),23.14](P = 0.000,P = 0.000,P = 0.004,P = 0.000).The nicorandil group had the lowest score.There was no significant difference between nicorandil group and adenosine group(P = 0.771).3.Myocardial infarct size was(27.04 ± 2.45)% in the nitroglycerin group,(17.01 ± 1.13)% in the diltiazem group,(47.97 ± 1.22)% in the adenosine group and(34.95 ± 1.25)in the nicorandil group.IR group(55.51 ± 1.43)% had the largest infarct size in all the groups,and the difference was statistically significant(all P<0.01).There was statistically significant difference in the drug post-conditioning groups(all P<0.01),and the infarct size of diltiazem group was the smallest.4.The expression of mitochondrial ALDH2 m RNA in the nitroglycerin and nicorandil postconditioning groups were 0.0657±0.0050 and 0.0587 ± 0.0004,respectively.The expression levels of mitochondrial ALDH2 m RNA were 0.7463±0.0726 and 0.8339±0.0808 in N group,respectively IR group(P <0.05,P <0.05).There was no significant difference in the expression of mitochondrial ALDH2 m RNA between nitroglycerin and nicorandil after treatment(P>0.05).The expression of ALDH2 protein in N group was higher than that in I group.The expression of adenosine and diltiazem protein was low,and the expression of nitroglycerin and nicorandil protein was increased compared with I-R group.Conclusions: 1.Nitroglycerin,diltiazem,adenosine and nicorandil can improve the cardiac pump function after ischemia-reperfusion,reduce the arrhythmia score of reperfusion,reduce the area of myocardial infarct,Thereby reducing myocardial ischemia-reperfusion injury,the protection of myocardial play a role.2.Diltiazem and nicorandil improve cardiac pump function more;in post-treatmentRA,nicorandil and adenosine better;in reducing the area of myocardial infarction diltiazem,nitroglycerol better.3.Adenosine and diltiazem can not protect myocardium against ischemia / reperfusion injury by up-regulating the mechanism of mitochondrial ALDH2.4.Nitroglycerin and nicorandil may play an important role in protecting myocardium against ischemia/reperfusion injury by up-regulating the mechanism of mitochondrial ALDH2.ALDH2 may be one of the protective mechanisms of nitroglycerin and nicorandil on ischemia-reperfusion injury. |
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