Suppression by Metyrapone of the Adrenal Response

The effect of metyrapone on the augmented adrenal 17-hydroxycorticosteroid (17-OHCS) secretion induced by the administration of adrenocorticotrophin (ACTH) was investigated in dogs. A single intravenous injection of ACTH (1 i.u./kg) resulted in the markedly increased secretion of adrenal 17-OHCS; the peak was attained within 60 minutes, and sustained over 3 hours. At the time when the secretion rate caused by ACTH was at a maximum, an intravenous injection of metyrapone (40 mg or 60 mg/kg) produced a rapid and marked decrease in adrenal 17-OHCS secretion. This diminution occurred within 15 minutes and the effect was reversible