Aim:To observe the effects and potential mechanisms of electrical field stimulation (EFS) on cardiac fibroblasts (CFs) proliferation Methods:Cardiac fibroblasts were isolated from the neonatal SD rats and cultured in Dulbeccos modified Eagles medium (DMEM),cells of passage 3 were used for experiments.EFS was used as an irritant agent.CFs proliferation was assessed by a cell survival assay (MTT) and cell counts.Myocardial fibrosis was assessed by checking the expression of collagen Ⅰ and Ⅲ by western blotting.CaN activity was determined by activity assay kit.Nuclear factor of activated T cell (NFAT) isoforms expression was determined by RT-PCR.Green fluorescent protein (GFP)-tagged NFAT was used to detect NFAT nuclear translocation.