Effects of miR-26b-5p on L-type calcium channel in atrial cardiomyocytes of ischemic arrhythmia rats / 中华老年心脑血管病杂志

ABSTRACT

Objective To explore the regulatory effect of miR-26b-5p on PI3K/PIP3 signaling path-way and its effect on L-type calcium channel of atrial cardiomyocytes in rats with ischemic ar-rhythmia.Methods A total of 72 SD rats were randomly divided into sham operation group,mod-el group,LY294002 group,negative control group,overexpression group and combination group,with 12 rats in each group.In 24 h after corresponding intervention,rat model of ischemic arrhyth-mia was established in the other groups except the sham operation group(only thoracotomy but without ligation).During the modeling process,arrhythmia indexes were detected in each group,and Curtis-Walker scoring was used for arrhythmia score.Fluorescence quantitative PCR was em-ployed to detect the expression of miR-26b-5p in atrial myocardiocytes,whole-cell patch-clamp technique was used to record the ICa-L of atrial myocardiocytes,and Western blotting was applied to measure the expression of CACNA1C,calmodulin and PI3K/PIP3 pathway related proteins.Re-sults Compared with the model group,the number of left ventricular preventricular contrac-tions,duration of ventricular tachycardia,duration of ventricular fibrillation,arrhythmia score,ab-solute value of ICa-L peak density of atrial myocardiocytes,and expression levels of CACNA1C and calmodulin were significantly increased,and the levels of miR-26b-5p,p-PI3K,PIP3 and p-Akt were obviously decreased in the LY294002 group(P＜0.05).While the overexpression group had decreased number of left ventricular preventricular contractions,shorter duration of ventricular tachycardia,shorter duration of ventricular fibrillation,lower arrhythmia score,reduced absolute value of ICa-L peak density,and lower expression levels of CACNA1C and calmodulin,and in-creased levels of miR-26b-5p,p-PI3K,PIP3 and p-Akt than the model group(P＜0.05).The number of left ventricular preventricular contractions,duration of ventricular tachycardia,dura-tion of ventricular fibrillation,arrhythmia score,absolute value of ICa-L peak density and expres-sion levels of CACNA1C and calmodulin were significantly increased,and the expression of p-PI3K,PIP3 and p-Akt were obviously decreased(0.82±0.08 vs 1.09±0.11,0.91±0.09 vs 1.17± 0.11,0.94±0.09 vs 1.20±0.12,P＜0.05)in the combination group than the overexpression group.Conclusion Overexpression of miR-26b-5p may block the L-type calcium channel in atrial myocardiocytes in ischemic arrhythmia rats by activating PI3K/PIP3 related signaling pathway,and thus improve the performance of arrhythmia in rats.