Arpe 19 cells

ARPE-19 cells (ICell Bioscience, China) were used for the experiments and were cultured in 10 % fetal bovine serum (FBS)-supplemented (Gibco, USA) DMEM/F12 culture medium (Hyclone, USA) at 37 °C in a humidified atmosphere of 5 % CO₂. The experiments were performed using cultured ARPE-19 cells (passages two through four) that were grown until they exhibited a hexagonal shape and no visible pigmentation. Upon reaching 60–70 % confluence, the ARPE-19 cells were cultured for 24 h in FBS-free DMEM/F12 culture medium to achieve cell synchronization. We treated the cells with four different interventions. The cells were incubated with 0.1, 0.5, 2.5, 10, 12.5 ng/ml TGF-β1 and 0.1, 1, 10, 100, 1000 nM BK for 24 and 48 h. Cell Counting Kit-8 (CCK-8) (Beijing Zoman Biotechnology Co., Ltd., China) was applied to detect cell proliferation. In addition, after the ARPE-19 cells were pre-incubated with various concentrations (0.1, 1, 10, 100, 1000 nM) of BK for 30 min, they were coincubated with 10 ng/ml TGF-β1 for 24 and 48 h so that we could observe the effect of BK on TGF-β1-induced ARPE-19 cell proliferation. We pre-incubated the cells with 1 μM HOE-140 for 30 min before treating them with or without exogenous TGF-β1 and BK.