INFLUENCE OF NITRIC-OXIDE ON HYPOGLYCEMIA - OR ANGIOTENSIN II-STIMULATED ACTH AND GH SECRETION IN NORMAL MEN

In order to establish whether nitric oxide (NO) is involved in the reg ulation ct ACTH and/or GH secretion, normal male subjects were treated i.v. with the NO-synthase (NOS) inhibitor N-G-nitro-L-arginine methyl ester (t-NAME) (40 mu g/kg injected plus 50 mu g/kg infused over 60 m in) in basal conditions and/or during stimulation with insulin (0.15 I U/kg body weight in an i.v. bolus) to induce hypoglycemia (ITT) or ASP I ILE-5 angiotensin II (ANG II) (increasing doses of 4, 8 and 16 ng/k g/min, each dose for 20 min). The administration of L-NAME neither cha nged the basal secretion of ACTH and GH nor modified the hormonal resp onses to ANG II stimulation. Also the GH response during ITT remained unchanged in the presence of L-NAME. in contrast, the ACTH response to hypoglycemia was significantly higher when L-NAME was administered. T hese data suggest that in normal men NO has a negative effect on ACTH secretion, hut not GH secretion, in response to hypoglycemia. Furtherm ore, our results argue against a role of NO in the control of basal an d ANG II-stimulated ACTH and GH secretions.