Mitochondrial redox components of human adrenocortical steroid hydroxylases under physiological conditions and in focal hyperplasia of the zone fasciculata.

Cytochrome P450, aa3 and adrenodoxin were characterized in human adrenocortical mitochondria. Human adrenodoxin demonstrated a distinctive electron paramagnetic spectrum exhibiting anisotropic g values indicative of axial symmetry. The observed g values were (formula: see text). Adrenodoxin content of crude human adrenal mitochondria was 0.65 +/- 0.01 nmol/mg of mitochondrial protein and was in a stoichiometric 1:1 molar ration with cytochrome P450. Mitochondrial cytochrome P450 (0.62 nmol/mg mitochondrial protein) and aa3 (0.19 nmol/mg mitochondrial protein) levels were determined in a normal human adrenal A patient receiving ACTH (3d) demonstrated a doubling of P450 content, while cytochrome aa3 levels remained unchanged. ACTH plus hydrocortisone therapy (3d) increased both P450 and aa3 levels, however 24 h hydrocortisone therapy alone was without effect. An area of focal hyperplasia of the zona fasciculata also demonstrated P450 and aa3 levels elevated above the contralateral and normal human adrenal levels. The possibility of hormonal control of human adrenal mitochondrial cytochromes P450 and aa3 is suggested.