Cholesterol side-chain cleavage activity in the outer and inner zones of the adrenal cortex

Cholesterol side-chain cleavage activity in mitochondria isolated from the outer and inner zones of the guinea pig adrenal cortex was evaluated in order to clarify the role of the zona reticularis in steroidogenesis. It was found that side-chain cleavage activity was three times higher in the outer zone. In addition, ether stress increased side-chain cleavage activity in the outer zone but not the inner zone. The concentration of total and free cholesterol was also found to be higher in the outer zone. However, when exogenous cholesterol was added to mitochondria, there was no enhancement in side-chain cleavage activity in either zone.