Stimulatory Action of Adrenal Medulla and Catecholamines upon Hydroxylation of Steroids by Adrenocortical Homogenates

Summary 1. Conversion of progesterone to 17a,21-dihydroxycorticosteroids by homogenates of bovine adrenal cortex is markedly stimulated by addition of small amounts (15 mg/100 mg cortex) of medullary homogenate. Larger amounts produce additional, though relatively smaller increments. 2. The soluble fraction of medullary homogenates equivalent to 15 mg of medulla stimulates as much as the corresponding amount of whole homogenate. Larger amounts of this supernatant fraction do not produce additional increments. 3. Increments similar to those obtainable with 15 mg of medullary homogenate or medullary supernates are produced with 100 μg or less of D(-) epinephrine, D(-) norepinephrine, or D(-) isopropyl-norepinephrine. No further increment results from larger additions. 4. Total catecholamine content of 15 mg of medullary homogenate or corresponding supernatant fraction ranged from 80-115 μg, indicating that the stimulatory action of small amounts of medulla can be ascribed mainly to catecholamines. Additional increments produced by larger amounts of medulla are apparently due to contamination with cortical remnants and, possibly, an additional factor of unknown nature. 5. Exploratory experiments suggest that catecholamines accelerate C-21 and, perhaps, C-17, but not C-11 hydroxylations.