Arginine vasopressin and oxytocin responses to angiotensin II are mediated by AT1 receptor subtype in normal men

Chiodera, P.; Volpi, R.; Caiazza, A.; Giuliani, N.; Magotti, M.G.; Coiro, V.

Next »Metabolism - Clinical and Experimental
Volume 47, Issue 8 , Pages 893-896, August 1998

Arginine vasopressin and oxytocin responses to angiotensin II are mediated by AT1 receptor subtype in normal men☆

P. Chiodera
- Address reprint requests to P. Chiodera, MD, Catedra di Endocrinologia, Università di Parma, via Gramsci 14, 43100 Parma, Italy.
- Department of Internal Medicine, School of Medicine, University of Parma, Parma, Italy
- Division of Internal Medicine, Hospital of Fidenza, Fidenza, Italy
R. Volpi
- Department of Internal Medicine, School of Medicine, University of Parma, Parma, Italy
- Division of Internal Medicine, Hospital of Fidenza, Fidenza, Italy
A. Caiazza
- Department of Internal Medicine, School of Medicine, University of Parma, Parma, Italy
- Division of Internal Medicine, Hospital of Fidenza, Fidenza, Italy
N. Giuliani
- Department of Internal Medicine, School of Medicine, University of Parma, Parma, Italy
- Division of Internal Medicine, Hospital of Fidenza, Fidenza, Italy
M.G. Magotti
- Department of Internal Medicine, School of Medicine, University of Parma, Parma, Italy
- Division of Internal Medicine, Hospital of Fidenza, Fidenza, Italy
V. Coiro
- Department of Internal Medicine, School of Medicine, University of Parma, Parma, Italy
- Division of Internal Medicine, Hospital of Fidenza, Fidenza, Italy

Received 26 September 1997; accepted 10 February 1998.

Abstract

This study was performed to determine whether the stimulatory effect of plasma angiotensin II (ANG II) on arginine vasopressin (AVP) and oxytocin (OT) secretion in humans is mediated by AT1 subtype receptors. For this purpose, the effects of the AT1 receptor antagonist losartan (50 mg orally) or a placebo on the AVP and OT responses to ANG II (intravenous infusion for 60 minutes of successively increasing doses of 4, 8, and 16 ng/kg min; each dose for 20 minutes) administration were evaluated in seven normal men. In additional experiments, the same subjects were tested with losartan (50 mg orally) alone or placebo alone. Neither losartan nor placebo given alone modified the basal levels of AVP and OT. ANG II infusion induced significant increments in both serum AVP and OT levels (mean peaks were 1.55 and 1.41 times higher than baseline, respectively). Both hormonal responses to ANG II were completely abolished by pretreatment with losartan. These data provide evidence of AT1 receptor involvement in mediation of the ANG II-stimulating effect on AVP and OT secretion.

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