Comparison of mutagenicities in asalmonella reversion assay mediated by uninduced hepatocytes and hepatocytes from rats pretreated for 1 or 5 days with aroclor 1254

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Abstract
Hepatocytes prepared from rats pretreated for 5 days with 500 mg/kg Aroclor 1254 were found to be unsuitable for use in a modified Salmonella mutagenicity assay. These hepatocytes exhibited low viability, did not readily attach to plastic culture dishes, and produced mutagenicity responses with benzo[a]pyrene (B[a]P) and 2-aminofluorene (2AF) that were greatly enhanced by the addition of an NADPH-regenerating system (NADPH-RS). Shortening the Aroclor pretreatment time to 1 day resulted in hepatocytes that exhibited high viability and readily attached to plastic culture dishes. These hepatocytes produced higher numbers of revertants when used to assay the mutagenicities of B[a]P and 2AF than were produced using hepatocytes from animals that were pretreated for 5 days. These reversion frequencies were also higher than those produced using uninduced hepatocytes and were much less affected by the addition of NADPH-RS than were the reversions mediated by the 5-day preinduced hepatocytes. Liver homogenate postmitochondrial fractions (S9s), which were prepared from rats pretreated with Aroclor for 1 or 5 days, were nearly equal in their ability to mediate the mutagenicity of B[a]P and 2AF in the Salmonella/microsome reversion assay. Qualitative differences between the S9- and hepatocyte-mediated mutagenicity of 2AF were found, however. These results indicate that employing hepatocytes from rats pretreated with Aroclor for 1 day, rather than 5 days, results in an enzymatically induced, more-intact cell population that is capable of detecting the mutagenicity of B[a]P and 2AF in a modified Salmonella reversion assay.

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