Studies on the maintenance of cytochromes P‐450 and b5, monooxygenases and cytochrome reductases in primary cultures of rat hepatocytes

Abstract

The cytochrome P-450 content of rat hepatocytes declined rapidly over 72 h in culture, due primarily to denaturation to cytochrome P-420. Six different media were investigated for their ability to conserve cytochrome P-450 during culture, and the most successful was a modified Earle's medium. After 72 h culture in this medium, cytochromes P-450 and b ₅, NADH-cytochrome b ₅- and NADPH-cytochrome c-reductases were maintained at 40, 100, 35 and 52% of fresh cell values, respectively. Cytochrome P-450 showed differential functional stability during culture with ethoxyresorufin O-deethylation being more stable than either pentoxyphenoxazone O-depentylation or biphenyl 4-hydroxylation. Monooxygenase activities declined faster than did cytochrome P-450 content. This discrepancy was not explained by loss of the flavin nucleotides, FMN or FAD.