| Background:In patients with coronary disease, the morbidity, disability and fatality rate havegot greatly increased in recent years, while acute myocardial infarction (AMI) is thedirect factor resulting in death. Thus, timely diagnosis and reperfusion treatment areconsidered to notably reduce mortality and improve prognosis. Increasing clinicstudies have shown that about25%~30%AMI patients do not present typically at theearly stage on clinical features and electrocardiogram (ECG), which makes it moreimportant of myocardial biochemical marker in the diagnosis of early AMI. To date,cardiac troponin I (cTNI) has been regarded as “golden standard”，but its effect is stilllimited.Therefore，the exploration of new, earlier and more sensitive myocardialbiomarkers has been never stopped.Micro ribonucleic acid (microRNA，miRNA) is a member of highly conservativenoncoding small RNA (20-25nucleotides),miRNAs are post-transcriptional regulatorsthat bind to complementary sequences on target messenger RNA transcripts (mRNAs),usually resulting in translational repression or target degradation and genesilencing.Recently, miRNAs have been found to play an crucial role in heartdevelopment, myocarium hypertrophy, heart failure, arrhythmia, myocardial damage,apoptosis and ischemia.Further studies had shown elevated miRNAs in rats andhuman patients with AMI, e.g, the latest researches abroad provided evidence ofunusual expression of miRNA-1, miRNA-133a, miRNA-208a and miRNA-499inpatients with AMI, indicating that the above miRNAs may be valuable in AMIdiagnosis. However, more investigations are needed to draw a consistent conclusion.Objective:To evaluate the importance of circulating microRNA-1and microRNA-133a inthe early diagnosis of acute myocardial infarction (AMI).Methods: 1. Six rats received ligation of LAD were in the test group, while6rats withoutligation of LAD were in the sham-operated group. In both groups of rats, the aboveitems were assessed at0h,1h,2h,3h,6h,12h,24h and48h after the operationsoccurred.2.24patients with AMI were enrolled in this study as the test group, while20healthy volunteers as the control group. Quantitative real time polymerase chainreaction (qRT-PCR) was adopted to evaluate the serum microRNA-1,microRNA-133a, microRNA-208a and microRNA-499levels in patients with AMI at3h，6h，12h，24h，48h，72h after AMI onset.3. All data were analyzed with SPSS16.0software. P<0.05was considered to bestatistically significant.Results:1. In rats with AMI, serum microRNA-1, microRNA-133a were elevated at1hafter AMI onset and reached peak level at3h, then reduced to normal levels at12-24h.while in the sham-operated group the microRNAs remained undetectable. CirculatingmiRNA-1and miRNA-133a levels were40-220times higher than those insham-operated group (p<0.05).There was no significant difference ofmicroRNA-208a and microRNA-499in both groups.2. In patients with AMI serum microRNA-1was greatly increased at3h afterAMI occurred and reached the peak level, then reduced gradually to nearly normal at72h. MicroRNA-133a was notably elevated at6h after AMI onset, reached peak at12h, then reduced to normal at48h. The peak levels of microRNA-1andmicroRNA-133a were10-55times (p<0.05) compared to those in healthy volunteers,which remained very low. As for microRNA-208a and microRNA-499, there was nostatistic difference between the test group and the control group.3. Serum microRNA-1and microRNA-133a levels were correlated with the cTnIexpression. The peak time of microRNA-1was earlier than that of cTnI, while thepeak time of microRNA-133a was at the same time with cTnI.4. There was no relationship between circulating microRNA-1, microRNA-133alevels and the width of QRS waves in AMI, but miRNA-1level in those combined with ventricular arrhythmia microRNA-1level was3.5times higher than that in thosewithout ventricular arrhythmia.Conclusions:Evaluation of circulating microRNA-1and microRNA-133a may serve aspotential and novel biomarkers for the diagnosis of AMI at early stage. |
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