Down‐regulation of hepatic cytochrome P450 in chronic renal failure: role of uremic mediators

Chronic renal failure (CRF) is associated with a decrease in liver cytochrome P450 (P450). The mechanism remains poorly understood. The present study aimed to investigate the effects of the serum of rats with CRF on liver P450. Normal rat hepatocytes were incubated for 24 h with serum (concentration of 10%) from rats with CRF and from control animals in order to measure (1) total P450 level, (2) protein expression and mRNA levels of major P450 isoforms, and (3) some of their specific metabolic activities (N‐demethylation of erythromycin). Time‐course experiments (incubation time from 12 to 48 h) and dose‐response curves (concentration of serum ranging from 1 to 30%) have been conducted. In normal hepatocytes incubated for 24 h with serum (concentration of 10%) from rats with CRF, total P450 level, protein expression and mRNA levels of several P450 isoforms (CYP2C6, 2C11, 3A1 and 3A2) were decreased by more than 35% (P