Evaluation of a sensitive radioimmunoassay of plasma corticotropin using commercial reagents.

A radioimmunological method for the sensitive estimation of plasma corticotropin immunoreactivity (ACTH) using commercially available reagents is presented. The method involves silica extraction of corticotropin from plasma, desorption with acid protein solution, neutralization and subsequent radiomimmunoassay (RIA). [125I]corticotropin is added as internal standard to the plasma sample.

Short-term kinetics of serum adrenal steroids and plasma ACTH after a single dose of metyrapone in man.

The in vivo influence of metyrapone (M) on different adrenal enzymes has been studied by simultaneous measurement of serum progesterone (P), 17-hydroxyprogesterone (17-OHP), deoxycorticosterone (DOC), corticosterone (B), deoxycortisol (S), 18-hydroxydeoxycorticosterone (18-OHDOC), aldosterone and cortisol (F) as well as by the measurement of plasma ACTH before and after oral administration of 40 mg of M/kg at 08:15 in four healthy male subjects. The well known inhibitory effect of M on adrenal 11-hydroxylase is demonstrated by a decrease of serum F and B and synchronous increase of serum S and DOC after administration of M. The additional inhibition of 18-hydroxylase by M is documented by a decrease of serum 18-OHDOC in spite of a marked increase of serum DOC after M.

Evidence of adrenal 18-hydroxylase inhibition by metyrapone in man.

The influence of metyrapone (M) on the adrenal 18-hydroxylation was studied in two groups of healthy young men. In group I, serum concentrations of 18-OH-11-deoxycorticosterone (18-OH-DOC) fell significantly after a single oral dose of 40 mg/kg of M at 8.00 h, while those of 11-deoxycorticosterone (DOC) increased by a factor of about 500 within 4 hours after drug administration.