Cellular localization of cytochrome(s) P-450 metabolizing polycyclic aromatic hydrocarbons in the rat adrenal cortex

Cells were dispersed from the capsular, as well as the inner portion of female rat adrenal glands and subsequently separated on discontinuous Percoll gradients. The adrenal cells were distributed within a density interval ranging from 1.016 to 1.075 g/cm3 and different subpopulations showed distinct morphological appearances in suspension, as well as in culture. The total cells from the inner portion of the adrenals metabolized [14C]7,12-dimethylbenz(a)anthracene at a rate of 4.04 pmol/min 10(6) cells and synthesized corticosterone in response to ACTH stimulation at a rate of 1.07 micrograms/hr/10(6) cells. These activities were 4- and 2.5-fold higher, respectively, than the corresponding activities in cells isolated from the capsular portion. 7,12-Dimethylbenz(a)anthracene monoxygenase activity and ACTH-stimulated steroidogenesis were enriched in two subpopulations of cells obtained on the Percoll gradient and were estimated to be 13.1 pmol/min/10(6) cells and 3.21 micrograms/hr/10(6) cells, respectively, in the most active fraction (at the 1.034/1.040 g/cm3 interface). On the basis of cellular morphology, density and steroidogenic properties, it was concluded that adrenal 7,12-dimethylbenz(a)anthracene monoxygenase activity is localized mainly in the cells of the zona fasciculata.