[Long time HCB exposition of rats: influence on the porphyrin excretion in the urine and on the cytochrome P-450 in the liver (author's transl)].

Adult female Wistar rats were fed with a diet containing 0.05% HCB. About the 55th day of the experiments an increase of porphyrin and its precursors (ALA and PBG) in the urine of the rats can be measured. In contrast the induction of the O-dealcylation reaction of 7-ethoxycoumarin could be already measured 2 days after starting with the HCB feeding. The inhibition of the enzymatic reaction by metyrapone, naphthoflavone, tetrahydrofurane or CO/O2 presents neither the typical pattern of the phenobarbital type nor the typical pattern of the benzpyrene type of cytochrome P-450. When the animals became porphyric (about the 55th day of the HCB exposure) no qualitative changes in the cytochrome P-450 pattern could be demonstrated. The relationship between the enzyme induction in the liver and the porphyria following the HCB application is still remaining unclear.