BACKGROUND: Electrical remodeling at infarct border zone (IBZ) has been shown to contribute to the occurrence of ventricular arrhythmias after myocardial infarction (MI). Sema3A has been demonstrated to reduce the inducibility of ventricular arrhythmias. Neuropilin 1 (NRP1) is the receptor of Sema3A. In the present study, we investigated whether treatment with NRP1 can ameliorate electrical remodeling at IBZ after MI. METHODS AND RESULTS: Wistar rats underwent sham operation (n鈥?鈥?0), the ligation of left coronary artery (MI group, n鈥?鈥?0), MI with control adenovirus (Ad group, n鈥?鈥?0), and MI with NRP1 adenovirus (NRP1 group, n鈥?鈥?0). Eight weeks after treatment, electrophysiological properties including heart rate variability (HRV), monophasic action potential duration (MAPD), effective refractory period (ERP) and the inducibility of ventricular arrhythmias and the expression of arrhythmia-related ion channel proteins including Kv4.2, Kv4.3, KChIP2 and Kir2.1 at the IBZ of the left ventricle were examined. Compared with the MI or Ad group, NRP1 significantly increased HRV and shortened MAPD and ERP (all P鈥?鈥?.05). Inducibility of VT by electrophysiological study was significantly lower in the NRP1 group than in the MI or Ad group (P鈥?鈥?.05). The expression levels of Kv4.2, Kv4.3, KChIP2 and Kir2.1 proteins were significantly decreased in MI group and Ad group. In contrast, the expression levels of these proteins were restored in NRP1 group, which may represent the molecular basis of the NRP1-mediated inhibition of electrical remodeling. CONCLUSIONS: NRP1 can ameliorate electrical remodeling at IBZ after MI.