CYTOCHROME P450S OF ISOLATED RAT HEPATOCYTES IN SPHEROID AND MONOLAYER-CULTURES

The maintenance of cytochrome P450s (P450s) and NADPH-cytochrome P450 reductase (P450 reductase) in the monolayer and spheroid cultures of h epatocytes from male rats was examined. The content of total P450 in m onolayer culture decreased to almost none after 144 hr, whereas the le vel in spheroid culture remained within 6-13% of initial values during an incubation period of 144-192 hr. P450 2C11, a major P450 in male r at, in monolayer cells rapidly decreased in 144 hr, while the level in spheroid cells after 144 hr and 192 hr maintained 25% and 15%, respec tively, of initial level. On the other hand, P450 2A1 and P450 2E1 in both monolayer and spheroid cells rapidly decreased. P450 reductase in both cells showed a gradual decline reaching a level of 43-44% of the initial level at 96 hr, and remained within 16-17% of the initial val ue during an incubation period of 192 hr. These results indicate that P450 2C11 in spheroid cells maintained more stable than in the monolay er cells, and that P450 reductase in both cultures declined only moder ately, compared with P450s.