No abstract

In 1948, Mason and Sprague (1) reported the isolation of hydrocortisone from the urine of a patient with Cushing's syndrome, and thus provided evidence that hydrocortisone was produced by the human adrenal cortex. Subsequently, hydrocortisone was found to be one of the principal corticoids in human adrenal gland perfusates (2) and in human peripheral blood (3). These observations strongly suggest that hydrocortisone may be the principal corticosteroid secreted by the adrenal cortex of man. Recent studies (4, 5) utilizing hydrocortisone-4-Cli have elucidated much new information regarding the metabolism and physiological disposition in man of this naturally occurring adrenal steroid.The availability of labeled hydrocortisone has made possible the direct estimation of the magnitude of the reservoir of hydrocortisone in the body, and the rate at which new, non-isotopic hydrocortisone is synthesized in the body and enters the reservoir. This report is concerned with the experimental determination of the magnitude of the miscible pool of hydrocortisone and the rate of its turnover in man. These estimations depend upon serial measurements of the specific activity of circulating hydrocortisone after the infusion of trace quantities of hydrocortisone4-0C1 and analyses of these data utilizing conventional turnover calculations (6, 7). Observations have been made in normal subjects, and subjects receiving adrenocorticotropin and A1 cortisone (prednisone). MATERIALS AND METHODSNine normal subjects (7 male and 2 female) were used for these studies. Each subject received 1 to 2.5 microcuries of hydrocortisone-4-C' dissolved in 2 to 5 ml. of 10 per cent ethanol in sterile distilled water. The steroid was administered intravenously in the fasting state in the morning over a period of approximately 3 minutes. Heparinized blood samples (40 to 60 ml. each) were collected at 30 to 40-minute intervals after injection of the isotope.Procedure for determination of sPecific activity of circulating hydrocortisone Twenty-five to 35 ml. of plasma were extracted gently for 10 minutes on a rotator (Arthur H. Thomas Co., Catalog No. 3623) in a 700-ml. Erlenmeyer flask with 5 volumes of dichloromethane (purified by passing through a column of silica gel [5]).The plasma and solvent were gently transferred to a 200-ml. ground-glass stoppered cylinder, and the plasma removed by aspiration.The dichloromethane extract was washed successively with 'A volume of 0.01 N sodium hydroxide, 'As volume of 0.1 M acetic acid, and X5 volume of water.

The present report is concerned primarily with the physiological disposition and fate of hydrocortisone in man. Large doses of this steroid have been administered intravenously, and the rate of its disappearance from plasma has been determined in normal subjects and in patients with liver disease and various endocrinopathies. The following procedure is a modification of the recently published method of Silber and Porter (1):Principle-Hydrocortisone is extracted from plasma into dichloromethane. The dichloromethane extract is washed with aqueous alkali to remove a considerable amount of "blank" material. The dichloromethane is then shaken with a sulfuric acid-ethanol reagent, containing phenylhydrazine. The resulting colored product is measured in the acid phase spectrophotometrically at 410 mny. A correction for material in plasma reacting with sulfuric acid is made by treating an equal aliquot of dichloromethane extract of plasma with sulfuric acid-ethanol which contains no phenylhydrazine.