Mitochondrial membrane potential of HK- 1 cells after CK treatment. HK-1 cells were treated with CK ( 15 μ M) for 4 and 24 h. Mitochondrial membrane potential was examined by flow cytometry with JC-1 probe treatment. Aggregate form of JC-1 was present in mitochondria with high membrane potential, whereas its monomeric form appeared in mitochondria with low membrane potential. The aggregate and monomeric forms of JC-1 were detected by FL1 and FL2 detectors of flow cytometer, respectively. (A) Representative flow cytometry scatterplots were shown. The cell distribution in the Q4 area indicated the cells which had low mitochondrial membrane potential. (B) Mitochondrial membrane potential was presented in 580/530 nm ratio. The histogram showed the relative change of mitochondrial membrane potential to the control. ***P < 0.001 versus control at 4 h, ##P < 0.01 versus control at 24 h.