Corticotrophin-induced differentiation of mitochondria in rat adrenal cortical cells grown in primary tissue culture: effects of ethidium bromide

SUMMARY Foetal rat adrenals were grown in primary tissue culture. The effects of ethidium bromide on the adrenocorticotrophin (ACTH)-induced differentiation of the mitochondria of the cortical cells were examined. Ethidium bromide (1 μg/ml/day for 4 days) inhibited the morphological transformation of the mitochondria normally induced by ACTH. At the same time the steroid 11β-hydroxylating activity, which is associated with the inner mitochondrial membrane, was either partially or completely blocked. The ethidium bromide-treated cells contained mitochondria of varying sizes and with poorly developed inner membranes. The biochemical and morphological effects of ethidium bromide on the cortical cell mitochondria were only partially reversible.