REGULATION OF FIBRONECTIN MESSENGER-RNA EXPRESSION IN PRIMARY HEPATOCYTES IN RESPONSE TO EGF AND PHENOBARBITAL

Adult rat hepatocytes were cultured in serum free chemically defined MX- 83 medium. Fibronectin mRNA expression accumulated to high levels in primary cultures of hepatocytes and transcripts were detectable even after 2 hrs. However, the presence of phenobarbital (PB) in the culture medium led to a dose-dependent decrease in fibronectin mRNA levels concomitant to an increase of cytochrome P450-2B1 (CYP2B1) mRNA, whereas the coaddition of EGF reversed the suppressive effect of PB in a similar dose-dependent manner. Culturing hepatocytes on a fibronectin matrix partially inhibited the accumulation of cytochrome CYP2B-dependent pentoxyresorufin-O-depentylase (PROD) activities in the presence of the inductor PB. © 1993 Academic Press, Inc.