Adrenal secretion rates and adrenal tissue concentrations of pregnenolone, progesterone, 11 beta OH-androstenedione and some other steroids in young pigs and dogs.
1. The rates were measured at which a number of different steroids were secreted by the adrenal gland of the eviscerated and nephrectomized young pig and dog.2. In addition to cortisol and corticosterone the following steroids were consistently found to be present in the adrenal venous blood: pregnenolone, progesterone, 11betaOH-progesterone, androstenedione, 11betaOH-androstenedione and adrenosterone.3. The sum of the latter steroids could amount to as much as 30% of the total steroid secretion.4. A severe deficit in the blood volume increased the secretion of pregnenolone and the 17-oxo steroids in the pig.5. alpha-ethyltryptamine failed to inhibit ACTH release if the animals were eviscerated and nephrectomized, or if they were anaesthetized with chloralose instead of pentobarbitone sodium.6. The same steroids as in the adrenal venous blood were found in extracts from the adrenal glands of a number of species.7. The amount of individual steroids present in the adrenal gland of the stressed pig and dog was compared with the rate at which each had been secreted immediately before the excision of the gland.8. There was a positive correlation between the adrenal concentrations and the secretion rates of cortisol, the major glucocorticoid secreted by the pig and the dog.9. In contrast, the rate at which pregnenolone was secreted did not show a consistent relationship to its concentration in the gland.10. A storage mechanism for pregnenolone in the adrenal cortex is proposed.