The development of DT-diaphorase in rat liver and its induction by benzo(a)pyrene

The development of cytosolic DT-diaphorase--NAD(P)H dehydrogenase, quinone, EC 1.6.99.2--and its induction by benzo(a)pyrene has been studied in rat liver. DT-diaphorase belongs to the late suckling cluster, because the largest increase in activity can be observed 18 days after birth. A considerable activity is present, however, in the neonatal period. The activity of the enzyme can be prematurely induced by benzo(a)pyrene. A lag phase of 10 h can be observed before the activity of DT-diaphorase starts to increase. This increase in activity proved to be sensitive to inhibitors of mixed-function oxydase and RNA and DNA synthesis.