Expression of cytochromes P450 4F4 and 4F5 in infection and injury models of inflammation.

Lipopolysaccharide (LPS) treatment of rats suppresses CYP 4F4 and 4F5 expression by 50 and 40%, respectively, in a direct fashion occurring in the liver. This contention is borne out by essentially parallel dose-dependent changes observed upon treatment of rat hepatocyte cultures with LPS. An alternate avenue of triggering the inflammatory cascade is traumatic brain injury by controlled cortical impact. Such injury brings about a dramatic change in the expression of CYP 4F4 and 4F5 mRNA which reaches its greatest effect 24 h after impact compared with sham-operated but uninjured controls. At time points after 24 h the expression of both isoforms increases dramatically reaching highest levels at 2 weeks post-injury. These changes in mRNA expression are mirrored by changes in protein expression. The results are consistent with the notion that immediately after injury concentrations of leukotriene and prostaglandin mediators are elevated by decreased CYP 4F concentrations. As time after injury increases those conditions reverse. Increased CYP 4F expression leads to diminished concentrations of leukotriene and prostaglandin mediators and then to recovery and repair.

In vitro metabolism of chlorpromazine by cytochromes P450 4F4 and 4F5 and the inhibitory effect of imipramine.

The metabolism of chlorpromazine by expressed recombinant cytochromes P450 4F4 and 4F5 cloned from rat brain was analyzed to characterize the individual activities of the isoforms. Both isoforms metabolized chlorpromazine to both the N-demethylated and the S-oxide products. When isoforms were incubated with chlorpromazine in the presence of increasing concentrations of imipramine, imipramine significantly inhibited both N-demethylation and S-oxidation of chlorpromazine. A dilution of the serum fraction of anti-4F antibody was also found to significantly inhibit both S-oxidation and N-demethylation of chlorpromazine by both 4F4 and 4F5.

High-performance liquid chromatographic methods for the analysis of haloperidol and chlorpromazine metabolism in vitro by purified cytochrome P450 isoforms.

Sensitive HPLC methods for the resolution and quantitation of metabolites of both haloperidol and chlorpromazine metabolism have been developed for use in in vitro reconstitution assays with purified P450 isoforms. Separation of haloperidol metabolites was accomplished using a Hypersil CPS column with a mobile phase of 67% acetonitrile and 10 mM ammonium acetate, pH 5.4. Separation of chlorpromazine metabolites was achieved using an Ultrasphere cyano column with a mobile phase of 87.5% acetonitrile, 5% methanol, 3% 0.12 M sodium acetate, 3% 0.12 M ammonium acetate, 0.01% diethylamine and 0.01% triethylamine, pH 9.5. Sharp resolution was observed for haloperidol and three of its major metabolites and for chlorpromazine and five of its major metabolites. Varying levels and combinations of these metabolites are formed during in vitro incubations of parent compound with purified P450 isoforms 1A1 and 2B1 in a reconstituted system.