In vitro induction of cytochrome P450 enzymes in hepatocytes isolated from the regenerating rat liver.

Partial hepatectomy results in the loss of cytochrome P450 enzymes. During regeneration, the levels of cytochrome P450 activities, apoproteins and mRNA are reduced. Our present study investigated CYP1A, CYP2E1 and CYP3A induction in the cells of rat liver regenerating for 1, 3, 7, or 14 days. Hepatocytes were isolated from regenerating liver of hepatectomized rats and treated with enzyme inducers: 3-methylcholanthrene, imidazole and dexamethasone. CYP1A enzymes of the cells isolated from regenerating liver were inducible by 3-methylcholanthrene. The rate of induction of the cells from 3-day regenerating liver by 3-methylcholanthrene was three times higher than that of the hepatocytes of sham-operated rats. Dexamethasone caused about two- or three-fold stronger elevation of CYP3A in the cells of 1-, 3- and 7-day regenerating liver than in hepatocytes of sham-operated animals. However, the degree of CYP2E1 induction by imidazole was the same (about 2.5-fold) at each regenerating time as it was detected in the hepatocytes of sham-operated animals. In conclusion, the inducibility of the cells was retained at each regenerating time, but the degree of induction showed some differences.