Assessment of 11β-Hydroxylase Activity with Plasma Corticosterone, Deoxycorticosterone, Cortisol, and Deoxycortisol: Role of ACTH and Angiotensin

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Abstract
In this study we evaluated the role of ACTH and angiotensin on regulation of activities of 11β-hydroxylases of the adrenal cortex. The ratio of the plasma concentrations of 11 deoxycorticosterone (DOC) to plasma corticosterone (B) reflected the activity of the enzyme of the B and/or aldosterone pathways, and the ratio of plasma 11-deoxycortisol (S) to plasma cortisol (F) as the activity of the enzyme in the F pathway. In normal subjects, both ratios were significantly lower at 0800–0900 h (Doc to B,.01 ±.004, mean ± SE, n = 10; and S to F,.01 ±.003) than at 2000 h (DOC to B,.028 ±.024 and S to F,.015 ±.005). The plasma levels of DOC, B, S and F were all significantly lower at 2000–2100 h than at 0800–0900 h. In contrast 9 patients with Cushing's syndrome exhibited no diurnal change in the ratios. The ratios increased substantially following dexamethasone or metyrapone administration. A high or low salt diet and an angiotensin infusion produced no significant effect on the ratios. The plasma concentration of all four steroids was increased by more than 50% by an infusion of angiotensin. Four hours after administration of 80 mg of Lasix at 0800 h to 10 normal subjects, the ratios of DOC to B and S to F increased significantly (P <.02), an effect possibly related to a decreased secretion of ACTH. Conclusions: 1) 11β-hydroxylase activity of the B and/or aldosterone and F pathways appears to change in parallel with ACTH secretion, and 2) although angiotensin stimulates steroidogenesis of the pathways, it has no apparent effect on 11β- hydroxylase activity.