AJP - Regulatory, Integrative and Comparative Physiology, Vol 272, Issue 6 1912-R1917, Copyright © 1997 by American Physiological Society

ARTICLES

Renal, hormonal, and cardiovascular responses to chronic angiotensin I infusion in the ovine fetus

K. M. Moritz, K. Tangalakis and E. M. Wintour
Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Australia.

Long-term infusion of angiotensin I (ANG I) into the ovine fetus has been shown to cause excess accumulation of fetal fluid in the allantoic compartment. It was hypothesized that this resulted from sustained increases in fetal urine production, and the hormonal basis was examined. ANG I (6.7 micrograms/h, n = 6) or isotonic saline (n = 6) was infused for 3 days into chronically cannulated ovine fetuses (112-122 days of gestation). ANG I caused an immediate and progressive increase in mean arterial blood pressure (from 42 +/- 2 to 57 +/- 4 mmHg), increased urine flow rate (from 15 +/- 3 to 48 +/- 8 ml/h), and increased glomerular filtration rate (from 97 +/- 15 to 146 +/- 24 ml/h), without significant changes in fetal plasma concentrations of aldosterone, atrial natriuretic factor (ANF), adrenocorticotropin, or cortisol. There were substantial increases in sodium and chloride excretion, due to both increased fetal urine concentrations and fetal urine flow, without significant changes in urine osmolality (from 134 +/- 9 to 147 +/- 12 mosmol/kg water). There were no significant changes in any parameter in the saline-infused fetuses. Neither amniotic or allantoic fluid volume was significantly changed by ANG I infusion, but allantoic fluid Cl- concentration increased significantly. The conclusions are that ANG I caused a diuresis and natriuresis in the fetal sheep independent of changes in cortisol or ANF.

This article has been cited by other articles:

				K. M. Moritz, A. Jefferies, E. M. Wintour, and M. Dodic Fetal renal and blood pressure responses to steroid infusion after early prenatal treatment with dexamethasone Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2005; 288(1): R62 - R66. [Abstract] [Full Text] [PDF]

				A. Umur, M. J. C. Van Gemert, and M. G. Ross Amniotic fluid and hemodynamic model in monochorionic twin pregnancies and twin-twin transfusion syndrome Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2001; 280(5): R1499 - R1509. [Abstract] [Full Text] [PDF]

				K. M. Moritz, D. J. Campbell, and E. M. Wintour Angiotensin-(1-7) in the ovine fetus Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2001; 280(2): R404 - R409. [Abstract] [Full Text] [PDF]

				K. Moritz, I. Koukoulas, A. Albiston, and E. M. Wintour Angiotensin II infusion to the midgestation ovine fetus: effects on the fetal kidney Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2000; 279(4): R1290 - R1297. [Abstract] [Full Text] [PDF]

				T. J. Roberts, M. J. M. Nijland, L. Williams, and M. G. Ross Fetal diuretic responses to maternal hyponatremia: contribution of placental sodium gradient J Appl Physiol, October 1, 1999; 87(4): 1440 - 1447. [Abstract] [Full Text] [PDF]