Cytotoxicity of 7-ketocholesterol toward cultured rat hepatocytes and the effect of vitamin E

The effects of 7-ketocholesterol on rat hepatocytes prepared by collagenase perfusion were examined, The viability of cells incubated with 100 mu M 7-ketocholesterol was significantly lower than those with cholesterol, although the LDH activity in the cultured medium remained unchanged during the incubation, Hepatocytes treated with 7-ketocholesterol produced large amounts of . NO and O-2(-) in the early stage of incubation, Treatment of the hepatocytes with Carboxy-PTIO, which selectively scavenged . NO, or with L-NMMA, an inhibitor of . NO synthase, increased the cell viability, The addition of 7-ketocholesterol to the culture medium tended to increase the ratio of total sterol to phospholipid of the hepatocytes in a time-dependent manner without changing the content of phospholipid, No lipid peroxidation or oxidation of the cellular SH groups, protein SH and glutathione, was apparent, Vitamin E added Ih before the addition of 7-ketocholesterol prevented the hepatocytes from cell death by suppressing the incorporation of 7-ketocholesterol into the hepatocytes and by scavenging O-2(-).