Cytochrome P-450 content and aldrin epoxidation to dieldrin in isolated rat hepatocytes

A rat hepatocyte suspension effectively epoxidized aldrin to dieldrin with a V_max of 7.19 mol/mol P-450/min and a K_m of 9.27 μM. Viability and metabolic activity were stable for 6 hr after isolation when cells were maintained at room temperature (20°C) with the gentle introduction of $\text{O}{}_2\text{CO}{}_2$ onto the surface of the suspension. The cytochrome P-450 content of the suspension was 303 pmol/10⁶ cells. Primary maintenance culture of the cells also epoxidized aldrin. During culture for 3 days, metabolic activity decreased slowly day by day. Metabolic activity of microsomal fraction from rat liver was also examined. Microsomes epoxidized aldrin with a V_max of 5.11 mol/mol P-450/min and a K_m of 1.64 μM. Significant loss of some subspecies of cytochrome P-450 during fractionation of liver homogenate was indicated.