Abstract:  Objective To detect the expressions of miRNA - 1 and miRNA - 21 and to investigate the relationship between myocardial remodeling and changes of myocardial function. Methods The myocardial infarction model of mice were prepared. Seventy-two model mice were divided into model group (MI group), intervention group 1 (miRNA-1 blocker was injected into infarct area) and intervention group 2 (miRNA-21 lentivirus carrier was injected into infarct area), 24 mice for each group. The ultrasonic instrument was used to measure the cardiac function indexes of the myocardial infarction model and evaluate the degree of cardiac function and ventricular remodeling. Fluorescence quantitative PCR was used to detect the expressions of miRNA -1 and miRNA-21. Results The expression of miRNA-1 was elevated at 4 weeks after MI, and reached the highest expression level at 12 weeks. The expression of miRNA-1 was decreased in all periods after the injection of miRNA-1 antagonist. MiRNA-21 showed a slight increase in 4 weeks after MI, followed by a decreasing trend. After injection of miRNA– 21 lentiviral vectors, the elevated miRNA-21 expression was obtained at various times. After injection with miRNA-1 antagonist, LVDD and LVmass showed improvement in 8 weeks and 12 weeks after MI. LVEF was significantly improved in 8 weeks and 12 weeks. MiRNA-21 lentiviral vectors were injected, and LVDD was reduced in 12 weeks. LVmass and LVEF were significantly improved in 12 weeks after MI. Conclusion In the process of myocardial infarction, miRNA-1 and miRNA-21 are involved in the regulation of heart failure and ventricular remodeling.

Key words: microRNAs, myocardial infarction, heart failure, ventricular remodeling, mice, inbred C57BL