Cadmium Induced Oxidative Damage Of Porcine Kidney Cells(PK-15)and Protective Effect Of N-acetylcysteine

In order to study the oxdative damage of Porcine Kidney cells(PK-15)induced by Cd and protection effect of NAC,PK-15 cells were treated with different Cd concentrations(0,2,4,6,8,10 μmol/L)for 24 h and different treatment times(0,6,12,18,24 h)of 8 μmol/L Cd by MTT assay,microexamination,fluorescence staining,enzyme activity detection,comet assay,electrophoresis.PK-15 cells were treated with 8 μmol/L Cd and 500μmol/L NAC combined treatment for 24 h to investigating alleviation effect of NAC on oxdative damage induced by cadmium.The aim of this study was to explore the toxicity damage of Cd on PK-15 cells,and to provide a scientific basis for the toxicity research of heavy metal pollution on mammalian kidney.There are three contents in our study:The first,the result of MTT assay showed that Cd treatment significantly inhibited the viability of PK-15 cells in dose-dependent and time-dependent manner;the optical microscope showed that the PK-15 cells became round,wrinkled and shedding;the levels of ROS gradually increased;obvious changes on ultrastructure were observed by transmission electron microscope(TEM),including chromatin condensation,and swelling of mitochondria and reduction of cristae number in PK-15 cells;the activities of T-SOD and GSH increased,whereas the activities of CAT decreased by the different kits.The second,the result of comet assay showed that the trailing phenomenon gradually increased with the time-and concentration-effect relationship in PK-15 cells;agarose gel electrophoresis manifested ladder-like bands with a size of 180-200 bp or its integral multiple;apoptotic cells which nucleolus were pyknosis and fragmentation by Hoechst staining;the results of flow cytometry showed that the reduction of mitochondrial membrane potential in concentration-dependent manner.The third,compared with Cd treatment group,the activities of PK-15 cells prominently increased after NAC and Cd combined treatment;the fluorescence intensity of ROS was weaker;the extent of DNA damage reduced;the phenomenon of nuclear chromatin condensation and fracture was alleviated.It is indicate that NAC can inhibit the toxic damage of Cd.Conclusions:Firstly,Cd could inhibit cell activities by inducing the increasing of intracellular ROS and destroy mitochondrial structure,antioxidation system imbalance.Secondly,Cd destroyed the structure of DNA and induced DNA fragmentation,decreased mitochondrial membrane potential,followed by inducing cell apoptosis.Thirdly,NAC alleviated oxdative damage of PK-15 cells induced by Cd,indicating that oxidative stress is the mechanism of Cd-induced PK-15 cell injuries.