Abstract: Objective To explore the expression of junctophilin 2(JP2)and fibroblast growth factor 23(FGF23)in a rabbit model of atrial fibrillation mediated-cardiomyopathy(AMC). Methods Rabbit models of atrial fibrillation (AF) were developed through rapid atrial stimulation and then divided into three groups: control group (pacemakers implanted without pacing, n=6), AF group (pacing with ejection fraction decrease ＜10%,n=5), and AMC group (pacing with ejection fraction decrease ≥10%, n=6).Echocardiography was performed to detect left ventricular end-diastolic diameter(LVEDD),left ventricular end-systolic diameter(LVESD) and left ventricular ejection fraction(LVEF). JP2 and FGF23 were detected by ELISA method.Western blot and RT-qPCR were conducted to detect protein and mRNA expression of JP2 and FGF23. Results Left atrial diameter, right atrial diameter and right ventricular diameter increased and LVEF decreased in the AMC group as compared with the control group. AMC group had lower LVEF and larger aorta and right ventricle diameter. Compared with the control group, the expression of FGF23(P＜0.001)and JP2(P＜0.01)in left atrial cardiomyocytes was significantly increased in the AF group, while the expression of JP2 was decreased in the AMC group(P＜0.001).AMC group had lower expression of JP2 and FGF23 compared with AF group. Compared to the control group,plasma concentration of JP2 and FGF23 increased in the AF group and FGF23 plasma concentration increased in the AMC group. Plasma concentration of FGF23 and JP2 was lower in AMC group than that in AF group . Conclusions FGF23 expression increased and JP2 expression decreased as found in the rabbit AMC model.

Key words: atrial fibrillation, atrial fibrillation mediated-cardiomyopathy, fibroblast growth factor 23, junctophilin 2