Chronic ouabain infusion does not cause hypertension in sheep.
Pidgeon, Grant B., A. Mark Richards, M. Gary Nicholls, Chris J.
Charles, Miriam T. Rademaker, Kelvin L. Lynn, Ross R. Bailey, Lynley
K. Lewis, Tim G. Yandle Departments Of Nephrology, Cardiology, and
Endocrinology, Christchurch Hospital, Christchurch, New Zealand.
Departments of Nephrology, Medicine and Endocrinology, Christchurch
Hospital, Christchurch, NEW ZEALAND, Fax No: 64 3 364 0935, Telephone
No: 64 3 364 0825
APStracts 2:0236E, 1995.
Ouabain is claimed to be a hormone of adrenal origin, capable of
raising arterial pressure in rats. We infused ouabain into conscious
sheep under carefully controlled circumstances to determine its
effects on blood pressure, urine electrolytes and vasoactive
hormones. Eight healthy ewes were studied while taking a constant
intake of dietary sodium and potassium. Ouabain infusion at 0.25mg
daily over 22 days reduced heart rate and arterial pressure, and had
no effect on pressor-responsiveness to incremental intravenous
infusions of angiotensin II. Ouabain induced minor, but statistically
significant, decrements in urine volume, urinary sodium excretion,
plasma renin and angiotensin II concentrations, and a rise in plasma
aldosterone and cortisol. Plasma ouabain levels averaged 1.37+/
-0.28nmol/l during ouabain infusion. In conclusion, high-dose chronic
ouabain infusion in sheep did not elevate arterial pressure or alter
pressor responsiveness to angiotensin II, was antidiuretic and
antinatriuretic, and induced minor perturbations in circulating
renin, angiotensin II, aldosterone and cortisol.
Received 28 June 1995; accepted in final form 12 October 1995.
APS Manuscript Number E297-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95