Comparative cytotoxicity of high-osmolar and low-osmolar contrast media on HKCs in vitro

Radiocontrast-induced nephropathy is a clinically important complication of intravascularly applied radiocontrast media. A predominant toxic effect of contrast media on renal tubules has been shown in previous clinical trials and animal experiments. Bax and Bcl-2 are members of the Bcl-2 family. Caspases are a family of cell death proteases, caspase-3 is one of the key executioners of apoptosis. In this study, we evaluated the cytotoxicity of high-osmolar contrast media (HOCM; diatrizoate) and low-osmolar contrast media (LOCM; iohexol) on human renal tubular epithelial cells (HKCs), and determined the regulatory roles of Bax/Bcl-2 and caspase-3 on apoptosis induced by contrast media (CM) in HKCs. An HKC line was used. Experiments were divided into 7 groups: the HOCM group with iodine 111 mg/mL, HOCM group with iodine 74 mg/mL, LOCM group with iodine 111 mg/mL, LOCM group with iodine 74 mg/mL, mannitol high-osmolar control group, mannitol low-osmolar control group and a culture media control group . The cytotoxicity of HOCM and LOCM were evaluated by cell proliferation and viability assay (MTT assay) and lactate dehydrogenase (LDH) release. Apoptosis were assessed by Hochest 33258 fluorescence-stained cytospins, TUNEL staining, DNA agarose gel electrophoresis, electron microscope and flow cytometric DNA analysis. The protein ex-pression of Bax/Bcl-2 was determined by Western blot analysis, and caspase-3 activity was also determined by the fluo-rometric method. Compared with the control group, LDH levels increased significantly (p