| Abstract: | Aryl hydrocarbon hydroxylase (AHH) activity and epoxyde hydrase (EH) activity have been found in Rat liver nucleoli obtained from untreated (C) and methylcholanthrene (MC) pretreated Rats. Electron microscopic observations of nucleolar preparations did not reveal significant contamination either by intact nuclei or by nuclear membranes. Very low but detectable activity of NADPH cytochrome C reductase was found in the nucleoli. Nucleolar preparations revealed little AHH activity (12-18 pmoles/min/mg). AHH was inducible by MC in nuclei but not in nucleoli. The presence of EH in nucleoli was demonstrated with phenanthrene 9,10-oxide (550-620 pmoles/min/mg) and benzopyrene 4,5-oxide (92-116 pmoles/min/mg). These values were lower than those obtained using intact nuclei. The addition of TCPO (10(-4) M) inhibited EH activity. |
