AJP - Endocrinology and Metabolism, Vol 267, Issue 5 E642-E647, Copyright © 1994 by American Physiological Society
Effect of ouabain on pressor responsiveness in normal man
G. B. Pidgeon, A. M. Richards, M. G. Nicholls, R. R. Bailey, K. L. Lynn, L. K. Lewis and T. G. Yandle
Department of Nephrology, Christchurch Hospital, New Zealand.
To assess the effects of ouabain on pressor and vasoactive hormone
responsiveness, 10 healthy volunteers were pretreated with ouabain (0.5 mg
i.v. 42 and 18 h before study) or placebo before pressor challenge with
angiotensin II (ANG II; 2, 4, and 8 ng.kg-1.min-1 for 30 min/dose) and
norepinephrine (NE; 5, 15, and 45 ng.kg-1.min-1 for 15 min/dose). There
were no differences at baseline between the two study days regarding mean
arterial pressure (MAP) or heart rate. Baseline pulse pressure, however,
was significantly greater after ouabain (47 +/- 3 vs. 41 +/- 1 mmHg; P <
0.05). The mean maximum increments in MAP during ANG II and NE infusions
were 17.5 +/- 1.1 and 10.5 +/- 1.3 (SE) mmHg, respectively, after ouabain
and 19.2 +/- 1.3 and 10.4 +/- 1.5 mmHg after placebo (not significant). The
mean heart rate was lower during both infusion periods on the ouabain study
day compared with control (P < 0.05). Baseline plasma levels of ANG II,
aldosterone, plasma renin activity, atrial and brain natriuretic peptide,
guanosine 3',5'-cyclic monophosphate, NE, and epinephrine and achieved
levels during the two infusions were similar on the two study days. We
conclude that short-term ouabain administration does not alter pressor
responsiveness or plasma levels of vasoactive hormones in healthy
volunteers.
