The Effect And Mechanism Of Mitochondrial Reactive Oxygen Species On Ventricular Arrhythmia-sudden Cardiac Death Induced By Acute Myocardial Ischemia

Background and aimsIschemic heart disease(IHD)is one of the most important causes of death worldwide,which mainly occurs in form of sudden cardiac death(SCD).At present,sudden death related to IHD is still increasing at home and abroad,and it has become a serious public health problem.The main mechanism of SCD induced by MI is fatal ventricular arrhythmia(FVA);the related deaths are common subjects in the forensic identification.Our preliminary work found that the incidence of SCD at the super early stage of myocardial ischemia(MI)was up to 38.9%.Based on metabolomic,lipidomic and proteomic researches,we found that mitochondrial dysfunction and oxidative stress were critical factors involved in the process FVA-SCD occurence.Therefore,in this study,we produced mouse models including ST segment myocardial ischemia(STEMI)-SCD induced by coronary artery ligation(CAL)and two drug intervention groups including pre-injecting apocynin(Apo)and Mito-TEMPO(MT).By detecting mitochondria-derived and total reactive oxygen species(ROS)levels and antioxidant capacity,we comprehensively evaluated the changes of m ROS and total ROS,and the relationship between redox imbalance and FVA occurence.We further analyzed phosphorylated proteome of the myocardia from model mice,to explicit the phosphorylated proteome mechanism related to oxidative stress during this process The study is expected to offer novel scientific evidence for the mechanism of FVA-SCD occurred in the super acute MI,and hopefully confers with new intervention targets for its clinical precise prevention and treatment.Materials and methodsCoronary artery ligation(CAL)-induced MI-SCD mouse model were established.According to the changes of ECG and survival,the model mice who with stable ECG and survived were defined as CAL-A group,and those with bradycardia and died after CAL were defined as CAL-SCD groups.Meanwhile,sham operation(SO)group was used as control.The drug intervention groups,NADPH oxidase inhibitor(Apo)and mitochondrial targeted antioxidant(MT),were defined as CAL+Apo group and CAL+MT group,respectively.The ECG of the whole process was monitored and recorded.To evaluate the balance of oxidative stress,antioxidant capacity and mitochondrial function in the process of FVA-SCD induced by MI at the super early stage,we detected oxidative stressand antioxidant capacities-related index(total ROS,m ROS,GSH/GSSG,SOD)and mitochondrial membrane potential(MMP)after retrieving ventricular samples from model mice.We further detected the myocardial phosphopeptides of the model mices and screened differentially expressed phosphoryled proteins among different groups,which were used to construct the metabolic pathway and the network according to gene ontology(GO)and pathway enrichment.Results1.The result of model mice establishment and their electrocardiographic characteristicsWe have produced 166 model mice,among which,SO group had 30 mice,CAL-A group had36 mice,CAL-SCD group had 30 mice,CAL + APO group had 35 mice and CAL+ MT group had 30 mice.CAL-SCD mice showed widened QRS wave amplitude,elevated ST segment,variant T wave and prolonged QTc in ECG.Mice from this group were more likely to die(46.7%)within 30 min after MI.CAL-A mice also showed elevated ST segment and they demonstrated relatively stable ECG and survived within 70 post MI.Mice from CAL+MT group and CAL+Apo group decreased QTc interval extension and reduced T wave variation from MI.2.Changes of phosphoproteome in ventricular myocardium of model miceA total of 1027 phosphorylated proteins were identified.There were 87 differentially expressed phosphorylated proteins between CAL-A group and SO group,there were 415 differentially expressed phosphorylated proteins between CAL-SCD group and SO group,there were 465 differentially expressed phosphorylated proteins between CAL+Apo group and CAL-SCD,there were 467 differentially expressed phosphorylated proteins between CAL+MT group and CAL-SCD group,there were 437 differentially expressed phosphorylated proteins between CAL-SCD group and CAL-A group.3.Outbreak of ROS occuring in the myocardia suffered from FVA destroyed antioxidant capacity,mitochon-drial function and disturbed phosphorylated proteome.Compared with CAL-A and SO groups,CAL-SCD had significantly higher levels of total ROS and m ROS,decreased antioxidant capacity,collapse of MMP and up-regulated the phosphoryla-tion proteins of ETC proteins involved in ROS production.4.Mito-TEMPO and apocynin can effectively inhibit oxidative stress and reverse the disturbed of phosphorylated proteins by FVA-SCD.The the intervention of Mito-TEMPO and apocynin both increased,survival rate of model mice after MI.The effect of Apo was not as well as that of MT within 30 min;conversely,Apo showed better results after 30 min of MI.Both interventions reduced the level of ROS in the myocardia,increase the antioxidant capacity,protect function of mithchondria(prevent the collapse of MMP),as well as reversed the disturbed phosphorylated proteins in CAL-SCD group.Conclusions1.In the ultra early stage of MI,the levels of total ROS and mitochondrial ROS increased significantly in a consistent trend,accompanied by the decrease of antioxidant capacity and the collapse of MMP,which were related to the high incidence of FVA-SCD at this MI stage.2.Mito-TEMPO can reduce the level of total ROS and m ROS,prevent arrhythmia and related SCD,as well as reversed SCD related phosphoproteome remodeling.