Objective. While it has been shown that atrial natriuretic factor (ANF) is able to inhibit CRH-stimulated ACTH secretion in vitro, in normal men conflicting results on its effect on ACTH/cortisol responses to insulin and CRH have been reported. Since no data are available concerning the possible influence of ANF on the hypothalamic-pituitary-adrenal axis in states of ACTH hypersecretion, the effect of ANF on pituitary-adrenal function in basal conditions and after CRH stimulation has been investigated in patients with Cushing's (n=4) and Addison's disease (n = 4). Design. On two different days all patients underwent the following procedures: (a) α-human ANF was infused, after a priming dose of 100 ng i.v., at a rate of 0.01 μg/kg/min over 5 hours. After 120 minutes of ANF infusion, oCRH (1 μg/kg) was i.v. injected as a bolus; (b) vehicle infusion was given over 5 hours and at 120 minutes oCRH was injected. Plasma ANF, ACTH, cortisol, aldosterone, renin activity and K+ were measured; heart rate and blood pressure were monitored. Results. In Cushing's disease plasma ANF rapidly increased within 30 minutes of the exogenous peptide infusion (from 27 ± 5 to 73 ± 14 pmol/1; mean ± SE), whereas in the vehicle study its concentration was unchanged. During the first 2 hours of both tests no significant modifications in ACTH levels were observed. After CRH the plasma ACTH peak was unchanged. Serum cortisol levels progressively declined during the first 2 hours of ANF infusion (from 778 ± 150 to 461 ± 48 nmol/l; P+ were only slightly affected on both occasions. Conclusions. (1) In patients with corticotrophin hypersecretion ANF does not influence basal and CRH-stimulated ACTH secretion; (2) in Cushing's disease ANF inhibits cortisol and aldosterone basal secretion; this effect is not mediated by ACTH and is over-ridden by CRH stimulation.
|Number of pages||6|
|Publication status||Published - 1994|
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