Objective To explore the possible mechanism of mitochondria damage in human kidney cells (HK-2 cells) in duced by lead acetate in vitro.
Methods Cultured HK-2 cells were exposed to different level of lead acetate. Mitochondrial membrane potential (MMP) and diphosphatidyl glycerol were detected by rhodamine 123 (Rh123) and 10-nonyl acridine orange (NAO). The release of cytochrome c (Cyt c) from mitochondria was detected by flow cytometry combined with immunofluorescence. Changes of diphosphatidyl glycerol and Cyt c were observed with mannitol treatment.
Results After exposed to lead acetate, MMP was descended in a dose-and time-dependent manner in HK-2 cells, significantly down from 4.56& #177;0.25 in normal control group to 2.90& #177;0.26 in 400 μmol/L exposure group and from 4.44& #177;0.20 in normal control group to 2.34& #177;0.50 in 12 h exposure group (P<0.05). The NAO fluorescence intensity (propidium iodide) of diphosphatidyl glycerol was declined in a dose-and timedependent manner, significantly down from 2.45& #177;0.18 in normal control group to 0.91& #177;0.18 in 400 μmol/L exposure group and from 2.52& #177;0.01 in normal control to 1.50& #177;0.05 in 24 h exposure group (P<0.05). Lead acetate induced Cyt c releasing from mitochondria and reduced the fluorescence intensity of Cyt c in a dose-and time-dependent manner. The treatment with 50 μmol/L mannitol recovered the fluorescence intensity of NAO to 2.30& #177;0.15 from 1.38& #177;0.14 and that of Cyt c to 14.20& #177;0.39 from 9.49& #177;0.31.
Conclusion Mitochondrial dysfunction could be induced by early exposure to lead acetate in HK-2 cells. And then, oxidative damage of diphosphatidyl glycerol would be enhanced, and the release of Cyt c from mitochondria could be induced. Finally, structural damage of mitochondria could be observed in HK-2 cells.
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