The effect of an NADPH-regenerating system on biphenyl metabolism in isolated rat hepatocytes.

Biphenyl 4-hydroxylation was studied in isolated rat hepatocytes. It was found that there was in inter-relationship between 4-hydroxylase activity and glucuronidase activity, removal of 4-hydroxybiphenyl by conjugation being necessary to stimulate a second phase of hydroxylation. Addition of an NADPH-regenerating system resulted in an initial depression of both processes, but later their activities were enhanced. This action could not be explained by the presence of non-viable cells.