The Expression Of Uncoupling Protein-2and Induced Nitric Oxide Synthase In Ischemia Preadaptation Myocardium

Background and objectiveUncoupling protein-2(UCP2) is a carrier protein, it has the ability to enhanceresistance to oxidative stress in myocardial cells, against myocardial ischemiareperfusion injury. It is located in the inner mitochondrial membrane, involved inoxidative phosphorylation and ATP synthesis uncoupling, played its role inmyocardial protection by inhibiting the production of reactive oxygen species. Invivo NOS has been found to have three different subtypes, eNOS (endothelial nitricoxide synthase) and INOS (inducible nitric oxide synthase) are considered to be themain subtypes associated with MIRI, their role being realized by catalyzing theproduction of NO. NO has vasodilatory activity, and its function is highly correlatedwith the concentration of NO.That is to say, low concentration has a protectiveeffect, but the high concentration has a toxic effect. Myocardial ischemicpreconditioning (IPC) is defined as in the shortest time intermittent and successivemyocardial ischemia being better to tolerate the long time ischemia, inhibitingmyocardial cell injury and protecting myocardial ischemia. Its role of protecting theischemic myocardium is to achieve the purpose of self protection of myocardium.On the hand it is to produce an endogenous protective protein by stimulation, on the other hand it is relized through the cell signal transduction pathways, changing thegene and protein expression of the pathway. As to the research level being moredeeply, It is observed that some drugs have a similar myocardial protective effect,which is drug pre-adaptation. At present, about the relationship between IPC andUCP2, the majority concentration is on the ischemic hypoxic stimulus, but lessconcentration is on the pharmacological preconditioning. About the role of iNOS inMIRI, the current research is more, but has great controversy. The majority ofscholars being devoted to the research of ACEI or ARB, have demonstrated thatthese drugs have the protection of ischemia reperfusion myocardial function. Thisexperiment by imitating the acute myocardial ischemia reperfusion injury in rats, Itfocuses on the detection of uncoupling protein2(UCP2) and inducible nitric oxidesynthase (I NOS), to observe the two kinds of factors in the MIRI rat myocardialtissue being pre-treated by enalapril of ACEI at the level of gene and protein changes,and try to explore its mechanism of action.Materials and methodsAdult male healthy SD rats, weight about250-300g, a total of35,were be used.After adaptive feed for5days, rats were randomly divided into three groups: controlgroup (sham group)7, ischemia reperfusion group (IR group)14, Bea Knapp Leighpreconditioning group (PIP group)14. PIP group was treated with Bea Knapp Leigh10mg/(kg d) for pretreatment by the way of saline gastric lavage, the control groupand ischemia-reperfusion group without any drug treatment, only2ml/d salinegastric lavage.After1weeks of pre-treatment,it was to prepare for myocardialischemia reperfusion injury (MIRI) model in rats. Sham group only weared linewithout ligation, IR group and PIP group and were thread ligation about30min, andthen were thread reperfusion about120min. At the end of the experiment, bloodsamples were detected phosphate kinase (CK) activity and propylene glycol (MDA)content in serum, and the tissue of myocardial ischemic area of left ventricle wasgetted in3groups of rats, the expression of RT-PCR was used to detect the leftventricular myocardial UCP2mRNA and I NOS mRNA, Western-Blotting methodwas used to detect the left ventricular UCP2and iNOS protein content. Data analysiswas used the SPSS17.0statistical software, to compare the level of variance about CK and MDA content of serum, UCP2and I NOS of gene and protein betweengroups.Result1)CK activity and MDA content in serumCompared with sham group, CK values of serum were significantly higher thanthat of IR group and PIP group (P<0.01); Compared with IR group, CK wasdecreased significantly in PIP group (P<0.01), the CK value is highest in IR group ofthe three group. Compared with sham group and PIP group, MDA values of serumwas significantly higher than that of IR group (P<0.01); PIP group is higher thansham group (P<0.05); serum MDA value was the highest in IR group of the threegroups2)The expression of myocardial UCP2Compared with sham group, Myocardial UCP2protein were significantlyhigher than IR group and PIP group (P<0.01), PIP group than IR group wassignificantly decreased (P<0.05); In the three group, UCP2content of the IR groupwas the highest.The changes of UCP2mRNA was parallel with protein levels inmyocardial tissue.3）The expression of myocardial iNOSCompared with sham group, IR group and PIP group myocardial iNOS proteincontent were obviously increased (P<0.01), PIP group is further elevated comparedto IR group (P<0.01); In the three group, the PIP group iNOS was the highest. Thechanges of iNOSmRNA was parallel with protein levels in myocardial tissue.Conclusion1）The UCP2and iNOS had a certain myocardial protective effect in MIRI;2) The myocardial protection of enalaprilat pretreatment may be related toreduce the expression of myocardial UCP2and increase the expression ofmyocardial iNOS;...