A high-performance liquid chromatography assay for measuring integrated biphenyl metabolism by intact cells: its use with rat liver and human liver and kidney.

A rapid, sensitive high-performance liquid chromatography assay with fluorescence detection for measuring biphenyl metabolism by intact cells has been developed. The assay does not require organic solvent extraction or enzymatic digestion for the measurement of hydroxybiphenyl conjugates. The lower limit of detectability for 4-hydroxybiphenyl is 5 pmol injected. Rat hepatocytes incubated with biphenyl form predominantly 4-hydroxybiphenyl sulfate with lesser amounts of 4-hydroxybiphenyl glucuronide and free hydroxybiphenyls, and small amounts of 3-hydroxybiphenyl sulfate and 3-hydroxybiphenyl glucuronide. Slices of fresh human liver incubated with biphenyl form predominantly 4-hydroxybiphenyl glucuronide with some free hydroxybiphenyl and small amounts of 4-hydroxybiphenyl sulfate. 4-Hydroxybiphenyl glucuronide formation by human liver shows a lag time that is not abolished by preincubating the liver without substrate. Human kidney slices incubated with biphenyl form 4-hydroxybiphenyl glucuronide and 4-hydroxybiphenyl sulfate at rates less than one-tenth those seen with human liver. Human kidney slices do not form detectable free hydroxybiphenyl. There is wide intersubject variability in the rates of hydroxybiphenyl metabolite formation by human liver and kidney.