cortodoxone and 18-hydroxydeoxycorticosterone

The function of the adrenal zona glomerulosa was studied in two pubertal siblings with the hypertensive virilizing form of congenital adrenal hyperplasia who had never been treated. Initially, their plasma 11-deoxycortisol and 11-deoxycorticosterone (DOC) levels were very high, PRA was suppressed, and plasma aldosterone and 18-hydroxycorticosterone (18-OHB) were undetectable. To selectively study zona glomerulosa function, the patients and five normal subjects were given dexamethasone (2 mg/day; thus suppressing zona fasciculata function), and their sodium intake was restricted to 10 mmol/day. After 3-5 days, the zona glomerulosa was stimulated with either angiotensin II or potassium chloride. The same protocol was repeated in the patients at various intervals up to 39 months after beginning maintenance therapy with dexamethasone (0.25 mg twice daily). PRA, plasma aldosterone, and 18-OHB remained low during the first 6 months of treatment. After the first year, PRA recovered, and the zona glomerulosa began to respond. Plasma aldosterone and 18-OHB levels reached normal basal and stimulated values in one of the patients after 2 yr of treatment, but remained subnormal after 39 months of treatment in the other patient. Both patients, however, had persistently elevated plasma DOC concentrations, suggesting slight but definite impairment of 11 beta-hydroxylation in the zona glomerulosa. We conclude that in spite of a severe and persistent 11 beta-/18-hydroxylation deficiency in the zona fasciculata, the zona glomerulosa can recover almost completely after prolonged treatment. Appropriate stimulation, however, discloses a minor 11 beta-hydroxylation impairment also in the zona glomerulosa. In addition, the lack of parallelism in zona glomerulosa 11 beta- and 18-hydroxylation of DOC provides evidence for the concept of different 18-hydroxylating systems in the adrenal cortex.

Topics: 18-Hydroxycorticosterone; Adolescent; Adrenal Cortex; Adrenal Hyperplasia, Congenital; Aldosterone; Angiotensin II; Child; Cortodoxone; Cytochrome P-450 CYP11B2; Desoxycorticosterone; Female; Humans; Hypertension; Male; Potassium Chloride; Renin; Steroid 11-beta-Hydroxylase; Steroid Hydroxylases

Whereas cytochrome P-45011 beta has been recently shown to catalyze the two-step conversion of corticosterone to aldosterone in the bovine and porcine adrenal cortex, the identity of the enzyme involved in the two final steps of aldosterone biosynthesis in the rat adrenal cortex is as yet unknown. Mitochondria from capsular adrenals of sodium-deficient, potassium-replete rats converted corticosterone to 18-hydroxycorticosterone and aldosterone at markedly higher rates than mitochondria from capsular adrenals of sodium-replete, potassium-deficient rats. However, the same preparations exhibited no difference in the 11 beta-hydroxylase activity, i.e. the conversion of deoxycorticosterone to corticosterone. Only mitochondria of zona glomerulosa from rats with stimulated aldosterone biosynthesis contained a 49K protein which showed a strong cross-reactivity with a monoclonal antibody raised against purified bovine cytochrome P-45011 beta. By contrast, a crossreactive protein with a molecular weight of 51K was found in mitochondria of zona fasciculata and in mitochondria of zona glomerulosa from rats with a suppressed aldosterone biosynthesis. These findings indicate the existence of two different forms of cytochrome P-45011 beta in the rat adrenal cortex, with only one of them, i.e. the 49K form, being capable of catalyzing the two final steps of aldosterone biosynthesis in situ.

Topics: 18-Hydroxycorticosterone; Adrenal Glands; Aldosterone; Animals; Corticosterone; Cortodoxone; Cytochrome P-450 Enzyme System; Desoxycorticosterone; Diet; Electrophoresis, Polyacrylamide Gel; Hydrocortisone; Immunoassay; Male; Mitochondria; Potassium; Rats; Sodium