Effects of pentachlorophenol on rat liver changes induced by hexachlorobenzene, with special reference to porphyria, and alterations in mixed function oxygenases.

Hexachlorobenzene (HCB, 1000 ppm) and 500 ppm pentachlorophenol (PCP) were fed separately or in combination to female Wistar rats. A control group was provided with standard food without HCB or PCP. Subgroups of 4 rats were killed after 1, 2, 4, 6 and 8 weeks. No significant difference was found between the amounts of HCB accumulated in the livers of the HCB and HCB + PCP fed rats. Administering HCB together with PCP caused a noticeable accumulation of PCP in the liver, compared to the results after administering HCB and PCP separately. In the HCB and HCB + PCP fed groups liver weight increased continuously during the experiments. Microsomal cytochrome P-450, NADPH-cytochrome c reductase, ethoxyresorufin O-de-ethylase, aminopyrine N-demethylase, and glucuronyl transferase increased to a maximum in 2-4 weeks in HCB and HCB + PCP fed rats. Pentachlorophenol accelerates the onset of HCB porphyria, in other words it increases the total urinary porphyrin excretion and causes an earlier disturbance of the porphyrin pattern.