Gene Chip Investigation Of Different Gene Expression And Influence Of Diltiazem Left Ventricular Injection On Myocardium Function In Myocardial Stunning Rat

Myocardial stunning is an ordinary clinical picture.Heyndrickx et al first described this phenomenon which systolic dysfunction delayed recovery after ischemic reperfusion in 1975.Braunwald et al proposed this concept of myocardial stunning in 1982.It was just considered as a laboratory phenomenon at the beginning that caused little attention.But after 1990s patients with ischemic heart disease can got coronary artery recanalization by many methods.Then the research of this phenomenon began to be hot spot.Though people investigated the pathogenesis of myocardial stunning by different experimental animals and methods,the precise pathogenesis was not clear.The main mechanism is comprised of oxygen free radical hypothesis, troponin degradation and calcium hypothesis.There have already been many researches showing that ischemic reperfusion could induce gene expression alter. This altered gene expression was just molecular basis of myocardial stunning.To understand which gene expression altered in myocardial stunning can not only reveal the molecular pathogenesis of myocardial stunning but also can treat this systolic dysfunction by target gene therapy and ensure myocardial stunning's self recovery.Perhaps this is the breakthrough of treatment of ischemic heart disease in the future.Although there had been many reaserches about myocardial stunning's alterative gene expression,they were restricted at a few genes. Reseachers need a new technology to investigate a great quantity of altered expressed genes.Gene chip is a high-flux triage techniques which develop with human genome project.It can screen differential expression of thousands of genes under the same experiment condition at the same time.The dependablity and efficiency of gene chip provide a new technology to investigate the different expression genes related to myocardial stunning.The characteristic of myocardial stunning is its latent recoverability. Someone think there is no need to treat a pathophysiological process which perhaps self-recovery.But many investigation had certified that repetat stunning can cause myocardial hibernation,and accordingly cause heart failure.Then it was of great importance to treat myocardial stunning promptly and effectively in prevention chronic cardiac failure.Most study and research had proved that intracellular calcium overload in reperfusion is a main reason of myocardial stunning.One of the active drug to prevent intracellular calcium overload is calcium antagonist.Diltiazem is a kind of selectivly calcium antagonist which can block Ca2+ enter cell through slow calcium channel and degrade intracellular Ca2+ concentration.In addition,as a calcium antagonist diltiazem can affect peripheral vascular smooth muscle cause blood vessel dilatation,lower vascular resistance,lessen cardiac afterloading,increase cardiac output,decrease myocardial oxygen consumption so as to lighten myocardial stunning.So calcium antagonist diltiazem may ameliorate this abnormity to treat myocardial stunning.ObjectiveTo investigate different gene expression of myocardial stunning and analyze the function of different expressed genes to investigate possible molecular pathogenesis of myocardial stunning so as to provide target gene for gene therapy in the future.To investigate therapeutic effect of calcium antagonist diltiazem left ventricular injection in myocardial stunning rat.Method1.Make rat myocardial stunning models by opening chest and reperfusion for 120 minutes after ligating anterior descending branch 20 minutes.2.Extract total RNA from anterior wall of myocardial stunning group and sham operated group in rat,use 27K Rat Genome Array from Beijing CapitalBio Corporation to scanning different expressed genes. 3.Undertake RT-PCR of a few high up-regulated ratio genes in gene chip to validate the dependability of the gene chip.4.Left ventricular inject diltiazem in myocardial stunning rat before ischemia,just at reperfusion and late in reperfusion and observe the index of hemodynamics.Result1.Myocardial stunning model of rats.Compared with sham operated group,the HR of myocardial stunning group after ischemia reperfusion increased,LVSP,LVDP,±LVdp/dt_max degraded,but cardiac enzyme has no statistical difference.2.Altered gene expression in myocardial stunning.Compared myocardial stunning group with sham operated group by gene chip, there were 292 differential expressed genes,among which 199 up-regulated and 93 down-regulated.For easy to further analyze,we select 41 genes with differential expression ratio more than 4.Compared HSP70,PAI-1,ATF-3,c-FOS which differential expression ratio were high in gene chip with house-keeping gene GADPH in RT-PCR,we found though differential expression ratio was not the same,the tendency was the same in two.So the result of gene chip was reliable.The biggest up-regulated expression ratio is 23.1.Functional classification of up-regulated genes includ 1.heat shock protein.2.immediate early genes.3.growth factor.4.apoptosis related genes.5.other genes possibly taking part in inflammatory reaction.3.Influence of different time left ventricular injection of diltiazem on myocardium function.Compared with sham operated group,HR of other groups increased 20min after ischemia reperfusion,LVSP,LVDP,LV±dp/dt_max degraded(P＜0.05).Compared with myocardial stunning group,injection diltiazem in ischemia period group LV±dp/dt_max obviously improved 60min after ischemia reperfusion(P＜0.05 ),LVSP,LVDP obviously improved 90min after ischemia reperfusion(P＜0.05),LV±dp/dt_max recover to baseline 120min after ischemia reperfusion.Injection diltiazem early in reperfusion group LV±dp/dt_max obviously improved 90min after ischemia reperfusion (P＜0.05),LVSP,LVDP obviously improved 120min after ischemia reperfusion (P＜0.05).But Injection diltiazem late in reperfusion group LVSP,LVDP,LV±dp/dt_max did not changed(P＞0.05).Conclusion1.Makeing rat myocardial stunning models by opening chest and ligating-reperfusion anterior descending branch is successful and feasible.2.Myocardial stunning up-regulated some genes can protect ischemia reperfusion myocardium.Promote these protective genes' expression maybe a treat target of ischemic heart disease in the future.3.Diltiazem injection in ischemia period or early in reperfusion can promote recovery of myocardial stunning.But diltiazem injection late in reperfusion has no effect on myocardial stunning.