ABSTRACT
AIM: To detect the effects of resveratrol (RSV) on the expression of microRNA-21 (miR-21) in primarily cultured neonatal rat atrial myocytes with electric remodeling induced by rapid electrical stimulation (RES).Furthermore, to find out the possible mechanism of miR-21 regulating electrical remodeling.METHODS: The neonatal rat atrial myocytes were isolated by double-enzyme (trypsin and collagenase I) digestion and differential adhesion method.The atrial fibrillation (AF) model was induced by RES.Atrial myocytes were randomly divided into 4 groups: control group, RSV group, RES group, and RSV+RES group.To further detect whether RSV regulated electric remodeling by miR-21, except the 4 groups, we add miR-21 over-expression group and miR-21 inhibitor group: RES+negative control (NC) group, RES+miR-21 mimics group, RES+miR-21 mimics+RSV group, RES+miR-21 inhibitor group, and RES+miR-21 inhibitor+RSV group.The optimal concentration and pretreatment time of resveratrol were determined by CCK-8 assay.The expression of miR-21 and the mRNA expression of L-type calcium channels CACNA1C and CACNB2 in atrial myocytes were detected by qPCR.The protein expression of L-type calcium channels Cav1.2 and Cavβ2 in the atrial myocytes was analyzed by Western blot.RESULTS: The expression of miR-21 in RES group was significantly increased compared with control group, while preconditioning with RSV decreased the expression of miR-21.Compared with RES+miR-21 mimics group, the expression of miR-21 in RES+miR-21 mimics+RSV group was significantly decreased.Meanwhile, the mRNA expression of CACNA1C and CACNB2, and the protein levels of Cav1.2 and Cavβ2 were increased (P<0.05).Compared with RES group, the expression of miR-21 in RES+miR-21 inhibitor group and RES+miR-21 inhibitor+RSV group was decreased, while the mRNA expression of CACNA1C and CACNB2, and the protein levels of Cav1.2 and Cavβ2 were increased.However, no difference of the expression of miR-21, the mRNA expression of CACNA1C and CACNB2, and the protein levels of Cav1.2 and Cavβ2 among RSV+RES, RES+miR-21 inhibitor and RES+miR-21 inhibitor+RSV groups was observed (P<0.05).CONCLUSION: In AF model induced by RES, RSV may reduce electric remodeling by inhibiting the expression of miR-21 and regulating the downstream target genes.