INSULIN HYPOGLYCAEMIA AND CHOLINERGIC BLOCKADE: RESPONSE OF PLASMA IMMUNOREACTIVE β-ENDORPHIN

Six normal subjects were studied to investigate the mechanisms involved in the release of immunoreactive β-endorphin (ir-βEP) in response to insulin hypoglycaemia. Insulin alone (0·2 U/kg body weight) was followed after a 30 min lag period by a ? 2·5 fold elevation of plasma ir-βEP, with a return to basal levels by 90 min. Concurrent infusion of 10% dextrose at 250 ml/h for 2 h prevented the increase in plasma ir-βEP levels, suggesting an effect of hypoglycaemia rather than a direct effect of insulin. Premedication with atropine 0·6 mg at -30 min was followed by hypoglycaemia equivalent to that seen with insulin alone, but no increase in plasma ir-βEP, suggesting the involvement of cholinergic mechanisms in the neural mediation of ir-βEP release in response to hypoglycaemia.     

β-LIPOTROPHIN AND β-ENDORPHIN PLASMA LEVELS DURING PREGNANCY

β-lipotrophin (β-LPH) and β-endorphin (β-EP) plasma levels were measured by radioimmunoassay after glass powder extraction and Sephadex G-75 column chromatography in plasma samples from controls (ten healthy males and twenty-six young women in early follicular phase), from eighty-two pregnant women in weeks 9–40 after their last menstrual period, from nine women just after delivery and the cord blood of their neonates, in fifteen mixed cord blood samples and in seven amniotic fluid samples obtained by amniocentesis. No sex differences were found in β-LPH (120·6 ± 8·5 pg/ml) or β-EP (31·1 ± 2·4 pg/ml) plasma levels or in their molar ratio (1·34 ± 0·09) (MR). β-LPH plasma levels increased in early pregnancy (13–16 weeks) (185·0 ± 27·1 pg/ml) and remained high until weeks 21–24, then declining to levels similar to those of controls. β-EP plasma levels were significantly depressed in weeks 9–12 (20·7 ± 5·3 pg/ml), subsequently increasing to a maximum at weeks 36–37 (42·7 ± 6·8 pg/ml). β-LPH/β-EP molar ratio was about double normal in early pregnancy and decreased to normal in the second half. The present data indicate that β-LPH and β-EP present different patterns throughout pregnancy and that β-EP levels increase progressively, reaching the highest concentrations at term. At delivery, both β-LPH and β-EP showed maximum values (β-LPH: 230·2 ± 20·4 pg/ml; β-EP: 78·0 ± 7·4 pg/ml) and a MR of 1·02 ± 0·10 indicating that stressful situations, such as labour, stimulate a simultaneous rise in β-LPH and β-EP plasma levels. Cord blood specimens showed a wide range of values (β-LPH:75–347 pg/ml; β-EP: 16–287 pg/ml) with a MR of 1·21 ± 0·14. Amniotic fluid samples obtained late in the third trimester of pregnancy were characterized by β-LPH levels of 119·4 ± 26·4 pg/ml and β-EP levels of 29·6 ± 7·5 pg/ml.     

THE EFFECT OF CHOLINERGIC BLOCKADE ON THE ACTH, β-ENDORPHIN AND CORTISOL RESPONSES TO INSULIN-INDUCED HYPOGLYCAEMIA

To assess the effect of cholinergic blockade on the ACTH, beta-endorphin and cortisol responses to insulin-induced hypoglycaemia, six healthy male volunteers each underwent two insulin tolerance tests in random order, separated by at least 1 week with and without atropine. ACTH levels were significantly greater at +45 min (mean +/- SEM, 223 +/- 21 pg/ml vs 148 +/- 15 pg/ml, P less than 0.01) and at +120 min (54 +/- 11 pg/ml vs 29 +/- 10 pg/ml, P less than 0.05). beta-endorphin levels were significantly greater at +30 min (170 +/- 45 pg/ml vs 96 +/- 32 pg/ml, P less than 0.05) and at +105 min (81 +/- 14 pg/ml vs 54 +/- 7 pg/ml, P less than 0.01). Cholinergic blockade had no effect on plasma glucose or cortisol concentrations. This study demonstrates that cholinergic blockade with atropine facilitates the ACTH and beta-endorphin responses to insulin-induced hypoglycaemia without altering the cortisol responses.     

INCREASED PLASMA CONCENTRATION OF N-TERMINAL β-LIPOTROPHIN AND UNBOUND CORTISOL DURING PREGNANCY

The plasma concentration of N-terminal β-lipotrophin (β-LPH), total and protein unbound cortisol, progesterone and the transcortin (CBG) binding parameters have been measured in 21 women in the early follicular phase and in 70 pregnant women at various stages of pregnancy. Results showed that the plasma CBG binding capacity and the concentrations of total cortisol and progesterone increased significantly at each trimester of pregnancy while the plasma concentration of unbound cortisol increased significantly only in the 2nd and the 3rd trimesters of pregnancy. In addition, a significant increase of N-terminal β-LPH level was observed during the 3rd trimester. By chromatography, it is demonstrated that during the 3rd trimester of pregnancy the β-LPH/γ-LPH molar ratio decreases dramatically and that the increase of N-terminal β-LPH concentration is mainly due to a two fold increase in γ-LPH concentration.     

β-ENDORPHIN AND β-MSH IN HUMAN PLASMA

The aim of this study was to establish whether or not a peptide with chromatographic and immunological properties of beta-endorphin exists in human plasma. Using direct chromatography under conditions designed to minimize generation of beta-endorphin and beta-MSH from beta-LPH, we invariably found a peptide with beta-endorphin immunoreactivity eluting in the position of beta h-endorphin on gel chromatography in samples of plasma from patients with elevated ACTH and LPH levels. beta-MSH was only found in the plasma of one patient with the ectopic ACTH syndrome.     

STUDIES ON THE MECHANISMS OF SOMATOSTATIN RELEASE AFTER INSULIN INDUCED HYPOGLYCAEMIA IN MAN

Insulin-induced hypoglycaemia, which stimulates gastric acid secretion, is associated with an increase in circulating somatostatin levels in man. In order to assess the mechanisms involved in this rise, six normal volunteers connected to a Biostator for continuous glucose monitoring were studied, on three separate occasions. On each occasion after basal blood sampling, 0.15 i.u./kg body weight of insulin was administered i.v. and further samples were obtained intermittently over 150 min. On one occasion, dextrose was infused by the Biostator to prevent hypoglycaemia, while on the other two, a constant infusion of either normal saline or the specific H2 antagonist cimetidine was administered. Insulin plus dextrose caused no significant changes in circulating somatostatin levels, whereas insulin plus saline was associated with a marked, sustained and significant rise in all subjects; insulin plus cimetidine also produced a rise but it was delayed; the area under the curve was significantly (P less than 0.05) greater with insulin plus saline than with insulin plus cimetidine. These results show that in man insulin itself does not stimulate somatostatin secretion directly, but indirectly via hypoglycaemia. Further, the inhibition of gastric acid secretion with cimetidine reduces somatostatin release during insulin-induced hypoglycaemia. This suggests that gastric acid may mediate somatostatin secretion associated with insulin-induced hypoglycaemia.     

PLASMA IMMUNOREACTIVE β-ENDORPHIN IS ELEVATED IN URAEMIA

Plasma immunoreactive-(IR) beta-endorphin (beta-EP) and beta-lipotrophin (beta-LPH) levels were measured in 15 adult uraemic patients on chronic haemodialysis. The presence of immunoreactivity eluting in the position of beta-EP was demonstrated following submission of pooled extracts of uraemic plasma to gel permeation chromatography on Sephadex G-50. To separate beta-EP from beta-LPH, pre-dialysis plasma extracts from six individual patients, and three pools of three patients each, were submitted to sequential immune-affinity chromatography and levels were measured by radioimmunoassay. In all cases, plasma IR beta-EP concentrations were markedly increased compared with normal subjects (m +/- SEM fmol/ml; 64.4 +/- 13.7 vs. 2.3 +/- 0.2). IR beta-LPH concentrations were also increased (m +/- SEM fmol/ml; 55.7 +/- 13.2 vs. normal 6.1 +/- 0.8). In addition, post-dialysis concentrations of plasma IR beta-EP and beta-LPH were lower than pre-dialysis levels (n = 4).     

THE EFFECT OF OXYTOCIN INFUSION ON ADENOHYPOPHYSIAL AND ADRENAL CORTICAL RESPONSES TO INSULIN-INDUCED HYPOGLYCAEMIA

The responses of plasma adrenocorticotrophin (ACTH), cortisol, growth hormone (GH) and prolactin to insulin-induced hypoglycaemia were studied in six lean male subjects (age 22-29 years). Intravenous insulin tests were performed with and without oxytocin infusion. Blood sugar nadir occurred at the onset of symptoms (time S) with no significant differences between oxytocin and saline infusion. During the oxytocin infusion mean plasma oxytocin increased from 1.9 pmol/l to 138 pmol/l. Peak increase in plasma ACTH (oxytocin 266 +/- 54 ng/l; saline 281 +/- 43 ng/l, mean +/- SEM) was at S + 10 min while peak plasma cortisol (oxytocin 680 +/- 47 nmol/l: saline 656 +/- 40 nmol/l) was measured at S +/- 60 min, peak GH (oxytocin 96 +/- 17.8 mU/l; saline 106 +/- 18.6 mU/l) at S + 60 min and prolactin (oxytocin 1332 +/- 239 mU/l; saline 1242 +/- 273 mU/l) at S + 30 min. There were no significant differences in plasma concentrations of ACTH, cortisol, GH or prolactin between saline and oxytocin infusion. The results indicate that oxytocin has no effect on plasma ACTH, cortisol, GH and prolactin responses to insulin-induced hypoglycaemia. In particular they fail to support previous studies which suggested an inhibitory role for oxytocin in ACTH secretion.     

PREVENTION BY SOMATOSTATIN OF RISE IN BLOOD PRESSURE AND PLASMA RENIN MEDIATED BY BETA-RECEPTOR STIMULATION

The interrelationships of increased plasma renin and elevated blood pressure following acute β-stimulation by orciprenaline and its prevention by somatostatin was studied in normal man. During somatostatin infusion basal values of renin and blood pressure were unchanged. Following orciprenaline both variables increased significantly. Combination of somatostatin and orciprenaline reduced the rise in plasma renin activity by 49%, mean arterial blood pressure by 21% and heart rate by 19%, compared with β-stimulation alone. The results indicate that the inhibitory action of somatostatin on plasma renin activity may be mediated via β-receptors. The lesser increase of blood pressure under somatostatin plus orciprenaline also indicates a possible inhibitory effect of somatostatin on β-adrenergic receptors.     

RESPONSES OF PLASMA OXYTOCIN AND ARGININE VASOPRESSIN TO NAUSEA INDUCED BY APOMORPHINE AND IPECACUANHA

Apomorphine, a centrally-acting emetic, was administered subcutaneously (50 micrograms/kg) to nine normal subjects (four male, five female; aged 22-36 years) and four patients with idiopathic diabetes insipidus (DI) (one male, three female; aged 24-49 years). In the normal subjects this stimulus caused nausea (and vomiting in seven of nine) with a latency of 9.5 +/- 0.9 min which was followed by a large increase in plasma arginine vasopressin (AVP) concentration (from 0.9 +/- 0.2 pmol/l to 249 +/- 104 pmol/l at 15 min after the onset of symptoms; mean +/- SEM, P less than 0.01). There was a small but significant increase in plasma oxytocin (OXT) concentration (from 1.6 +/- 0.4 pmol/l to 6.2 +/- 3.4 pmol/l; P less than 0.05). Mean arterial pressure (MAP) fell slightly (from 87 +/- 1.9 mm Hg to 71 +/- 4.4 mm Hg; P less than 0.05) 15 min after the onset of nausea; there was no change in blood haematocrit or plasma osmolality and sodium concentration. In the DI patients apomorphine produced nausea (with vomiting in three of four) with a latency of 10.0 +/- 1.4 min but failed to cause an increase in either plasma AVP or OXT. In the DI patients the fall in MAP did not reach statistical significance (83 +/- 4 mm Hg to 71 +/- 11 mm Hg); there was also no change in haematocrit, osmolality or sodium concentration. Ipecacuanha, an emetic with both peripheral and central actions, was administered orally to seven normal subjects (three male, four female; aged 22-36 years) six of whom also underwent apomorphine tests.(ABSTRACT TRUNCATED AT 250 WORDS)     

CORTISOL, GROWTH HORMONE AND PROLACTIN RESPONSES TO INSULIN-INDUCED HYPOGLYCAEMIA IN HYPERTHYROID PATIENTS BEFORE AND DURING β-ADRENOCEPTOR BLOCKADE

Two beta-adrenoceptor blocking agents, metoprolol (beta-1-selective) and propranolol (non-selective), were used in the treatment of hyperthyroid patients. The response of pituitary stress hormones to insulin-induced hypoglycaemia was investigated before and during beta-adrenoceptor blockage. Treatment with metoprolol (n=10) or propranolol (n=10) produced no changes in the cortisol or prolactin responses to hypoglycaemia. Moreover the growth hormone response remained unaltered during treatment with metoprolol. A small, but statistically significant, augmentation of growth hormone response was obtained during treatment with propranolol. When twelve subjects, euthyroid after final conventional treatment (surger), radioiodine or thyrostatic drugs), were re-examined, the cortisol and prolactin responses were unchanged, although growth hormone concentrations reached a slightly higher maximum value (P less than 0.01). It was concluded that treatment with beta-blocking agents in hyperthyroid subjects has no clinically important influence on the release of pituitary stress hormones during hypoglycaemia.     

THE EFFECTS OF A MET-ENKEPHALIN ANALOGUE ON ACTH, β-LPH, β-ENDORPHIN AND MET-ENKEPHALIN IN PATIENTS WITH ADRENOCORTICAL DISEASE

Thirteen patients with either Addison's disease, or Cushing's disease treated by bilateral adrenalectomy, were infused with the long-acting met-enkephalin analogue DAMME. In patients with Addison's disease significant and pronounced falls in ACTH and N- and C-terminal beta-LPH were seen; chromatography suggested that beta-endorphin fell concomitantly. Three out of four patients with Cushing's disease who had not received pituitary irradiation, also showed a decrease in plasma ACTH and N- and C-terminal beta-LPH; however, no change was seen in any of the irradiated patients. The changes were naloxone reversible. The levels of plasma met-enkephalin were normal and did not change after DAMME in any group of patients. These results are interpreted as suggesting that there are inhibitory opiate receptors controlling the release of ACTH, beta-LPH, and beta-endorphin.     

COMPARISON OF THE ACTH AND CORTISOL RESPONSES TO PROVOCATIVE TESTING WITH GLUCAGON AND INSULIN HYPOGLYCAEMIA IN NORMAL SUBJECTS

The glucagon stimulation test (GST) is often used to assess pituitary ACTH reserve, particularly when other tests are contra-indicated. In a preliminary investigation, in patients with pituitary disease, we failed to demonstrate the ACTH dependence of the cortisol response. We have therefore compared the ACTH, cortisol and glucose responses to glucagon (1 mg s.c.), insulin (0.2 U/kg i.v., ITT) and placebo in six healthy male volunteers, sampling every 10 min for 6 h. During the GST, mean +/- SD serum cortisol rose from 256 +/- 80 nmol/l to a peak of 481 +/- 164 nmol/l (range 289-717 nmol/l, P less than 0.01) in comparison with 280 +/- 81 nmol/l to 602 +/- 110 nmol/l (range 493-742 nmol/l) during the ITT (P less than 0.002). The mean peak cortisol levels achieved in the two tests did not differ significantly. In the GST, plasma ACTH rose from a mean basal value of 10.9 +/- 16.6 ng/l to a mean peak level of 123 +/- 76 ng/l (P less than 0.02) (ACTH ng/l x 0.225 = pmol/l). The corresponding values in the ITT were 7.1 +/- 16.2 ng/l and 263 +/- 91 ng/l (P less than 0.001). The mean peak ACTH level was significantly greater during the ITT (P less than 0.05). Thus the cortisol response was ACTH dependent in both the GST and the ITT in normal subjects. Furthermore, the ACTH response was of sufficient duration to be detected by the usual procedure of sampling every 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)     

THE HALF-LIFE OF ENDOGENOUS INSULIN AND C-PEPTIDE IN MAN ASSESSED BY SOMATOSTATIN SUPPRESSION

The in-vivo half-lives of insulin and C-peptide have been assessed in normal man by a method which examines the decline of endogenously produced insulin and C-peptide after somatostatin suppression of secretion. Venous blood samples were taken each minute from seven normal subjects: i.v. glucose (0.1 g/kg ideal body weight) was given over 1 min to stimulate secretion, followed by a bolus of 250 micrograms of somatostatin-14 and an infusion of a further 250 micrograms somatostatin-14 over the subsequent 30 min. Plasma samples were analysed for C-peptide, glucose and insulin. The initial mono-exponential half-lives over 8 min were 3.9 +/- 0.3 and 10.2 +/- 0.7 min respectively (mean +/- SEM), with subsequent slower declines. Log transformed insulin and C-peptide yielded biphasic declinations which were assessed by a two-pool model. The rate constant of clearance of insulin implied avid uptake, while the kinetics of C-peptide clearance were slower, and irreversible loss might be explained by glomerular filtration alone. The somatostatin suppression method of measuring hormone kinetics could be used for newly described hormones which are not available for in-vivo studies.     

SECRETION OF ACTH, LPH AND β-ENDORPHIN FROM HUMAN PITUITARY TUMOURS IN VITRO

Basal and stimulated secretion of immunoreactive ACTH, LPH and β-endorphin from four human pituitary tumours has been studied in vitro using a superfused, isolated cell system. Chromatography of cell secretions under acid-dissociating conditions demonstrated that the human tumour cells released immunoreactive peptides with the elution profiles of α_h (1–39) ACTH, β_h-LPH, γ_h-LPH and β_h-endorphin confirming that β_h-endorphin is secreted by human pituitary tumour cells and is not formed by enzymic cleavage from β_h-LPH in blood. No α- or β_h-MSH, nor any higher molecular weight forms of ACTH or LPH were detected. The cells from all four tumours responded to stimulation with rat stalk-median eminence extract (SME) and synthetic AVP with a concomitant release of ACTH, β-LPH, γ-LPH and γ-endorphin. In contrast to the isolated rat anterior pituitary cells, the pattern of responses to SME and AVP were indistinguishable and the release provoked by rat SME could be accounted for virtually entirely by its vasopressin content. No stimulation of release was observed when the cells were exposed to a variety of biogenic amines. Addition of hydrocortisone to the perfusion buffer of two tumours resulted in a slow inhibition of both basal and stimulated ACTH and LPH release. These data demonstrate that human pituitary tumour tissue from patients with Cushing's disease and Nelson's syndrome can be studied in vitro and that such studies may contribute to a greater understanding of the aetiology of these diseases.     

A COMPARISON OF THE EFFECT OF LEVODOPA AND SOMATOSTATIN ON THE PLASMA LEVELS OF GROWTH HORMONE, INSULIN, GLUCAGON AND PROLACTIN IN ACROMEGALY

The acute suppressive effects of L-dopa and somatostatin (growth hormone release inhibiting hormone) on the elevated plasma GH concentrations of seven patients with acromegaly were compared. In addition the effects of the two agents on fasting concentrations of plasma glucose, insulin, glucagon and prolactin were studied. In six of the seven patients hourly samples for GH assay were taken from 08.00 to 20.00 hours on a control day. Synthetic cyclic somatostatin (100 mug) was infused intravenously in an albumin/saline solution over 75 min with a Harvard constant infusion pump. Levodopa 500 mg was given orally. Somatostatin infusion produced a reduction in plasma GH concentrations in six of seven patients (mean reduction 55%). L-Dopa produced a reduction in plasma GH concentrations in the same six patients (mean reduction 52%). The minimum GH concentrations achieved in the two tests were comparable and did not differ significantly from the minimum GH concentrations recorded during the 12 h control study. Mean plasma insulin and glucagon concentrations were also significantly reduced during the somatostatin infusion (P less than 0-025; P less than 0-05 respectively). Plasma glucose concentrations did not change. L-Dopa did not alter mean plasma glucose, insulin or glucagon values. Somatostatin did not alter prolactin values but L-Dopa suppressed basal values to less than 2 ng/ml in five patients. This study shows that the plasma GH change after the administration of L-dopa and somatostatin in acromegaly is comparable and confirms the pancreatic effects of somatostatin.     

RESPONSE OF CIRCULATING SOMATOSTATIN, INSULIN, GASTRIN AND GIP, TO INTRADUODENAL INFUSION OF NUTRIENTS IN NORMAL MAN

We have studied the effect of direct infusion of nutrients into the duodenum of normal subjects on circulating plasma somatostatin, insulin, gastrin and gastric inhibitory polypeptide (GIP) levels. Six normal subjects were given on four separate occasions 150 ml of isotonic solutions containing 100 calories of carbohydrate, protein, or fat, and a control solution of saline, by infusion into the second part of the duodenum. Plasma somatostatin rose slightly after carbohydrate, mean basal 30 +/- 3 pg/ml, peak 46 +/- 16 pg/ml at 15 min; and more markedly after protein, peak 57 +/- 9 pg/ml at 30 min. However, fat was the most potent intraduodenal stimulus to plasma somatostatin release into circulation, peak 101 +/- 11 pg/ml at 30 min. The plasma insulin rise was greatest after carbohydrate, peak 68 +/- 10 i.u., but there was a significant rise after protein also, peak 34 +/- 6 i.u. Plasma gastrin rose significantly after protein only, peak 70 +/- 22 pg/ml. Plasma GIP rose markedly after carbohydrate, basal 506 +/- 50 pg/ml, peak 1480 +/- 120 pg/ml. Protein was also a potent stimulus of circulating plasma GIP release, peak 1200 +/- 190 pg/ml, while fat was the least potent, peak 730 +/- 190 pg/ml. Thus, calorie for calorie, fat is the most potent intraduodenal nutrient stimulus of circulating somatostatin. We postulate therefore that somatostatin may be an enterogastrone--a circulating hormone released by intraduodenal fat which inhibits gastric acid secretion. Fat is the least potent intraduodenal nutrient stimulus of circulating GIP release. This is evidence against the hypothesis that circulating GIP acts as an enterogastrone.     

PLASMA OXYTOCIN, ARGININE VASOPRESSIN AND ATRIAL NATRIURETIC PEPTIDE RESPONSES TO INSULIN-INDUCED HYPOGLYCAEMIA IN MAN

The changes in blood glucose, plasma oxytocin, plasma vasopressin, plasma atrial natriuretic peptide, serum osmolality, haematocrit and blood pressure were measured in response to acute insulin-induced hypoglycaemia in six normal male subjects. After the i.v. administration of insulin (0.15 U/kg), plasma concentrations of oxytocin and vasopressin increased rapidly in all subjects and were maximal 15 min after the acute hypoglycaemic reaction (R). Haematocrit increased at the time of the hypoglycaemic reaction, but there was no change in serum osmolality. Systolic blood pressure rose and diastolic blood pressure fell, but mean arterial blood pressure remained unchanged. No changes were demonstrated in plasma concentrations of atrial natriuretic peptide. The release of oxytocin and vasopressin in response to acute hypoglycaemia in man is probably caused by stimulation of the posterior pituitary gland via hypothalamic activation, and not by stimulation of osmoreceptors or baroreceptors.     

ACUTE DOPAMINERGIC BLOCKADE BY SULPIRIDE STIMULATES β-ENDORPHIN SECRETION IN PREGNANT WOMEN

The pars intermedia of the pituitary gland is well developed in most animal species but rudimentary in adult human subjects. Unlike the anterior pituitary, the intermediate lobe metabolizes proopiomelanocorticotrophin (POMC) mainly to beta-endorphin and to alpha-melanotrophin (alpha-MSH). This activity of the pars intermedia is under an inhibitory dopaminergic control. Biochemical and immunohistochemical evidence suggests the hyperplasia of the intermediate lobe during human pregnancy. The present study demonstrates that an acute dopaminergic blockade by sulpiride dramatically increases plasma concentrations of beta-endorphin in pregnant women but not in non-pregnant women providing functional evidence for the intermediate lobe hypothesis.     

APPARENT MINERALOCORTICOID EXCESS AND DEFICIENT 11β-OXIDATION OF CORTISOL IN A YOUNG FEMALE

A 19-year-old female, known to have had hypertension and hypokalemic alkalosis since the age of 9 months, was found to have suppressed renin, negligible plasma and urinary aldosterone and low plasma levels of other known sodium-retaining steroids. Despite the normal plasma cortisol the urinary excretion of 17-oxosteroids and 17-oxogenic steroids was low as was the cortisol secretion rate, suggesting a diminished metabolic clearance of cortisol. This was confirmed by the demonstration of a prolonged t 1/2 of 14C-cortisol. The abnormally high urinary excretion ratios of cortisol to cortisone, tetrahydracortisol to tetrahydrocortisone and 11-hydroxy-aetiocholanolone to 11-oxy-aetiocholanolone indicate that the diminished cortisol breakdown is the result of deficient 11 beta-oxidation. Moreover, the urinary excretion of free cortisol was elevated, probably due to diminished tubular reabsorption of cortisol. Hypokalemic alkalosis did not respond to spironolactone, but was partly corrected by amiloride. No response to dexamethasone was observed, but dexamethasone combined with aminogluthetimide normalized blood pressure and serum K. These findings support the involvement of a sodium-retaining, kaliuretic steroid in this rare syndrome.