Regional Hemodynamic Effects of a Digitalis Glycoside in the Conscious Dog with and without Experimental Heart Failure
Key result
Intravenous ouabain causes regional vasoconstriction and mesenteric vasodilatation in normal dogs, but increases blood flow to all beds in dogs with experimental heart failure.
Why the study?
Does intravenous ouabain alter regional hemodynamics in conscious dogs with and without experimental heart failure?
Population
8 normal conscious dogs and 6 conscious dogs with experimental heart failure produced by tricuspid avulsion…
Comparison
Intravenous ouabain 20 µg/kg vs Baseline and comparison between normal and heart…
Design
Preclinical
Follow-up
30 minutes
Authors
Discussion
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Implication
Differential ouabain effects in canine HF models warrant caution in translation; leaves open hemodynamic mechanisms for human study.
Key Points
- To examine the hemodynamic effects of ouabain in conscious dogs under normal conditions and with induced heart failure.
- Administered intravenous ouabain (20 µg/kg) to conscious dogs
- Measured blood flow in regional vascular beds using Doppler ultrasonic and electromagnetic flowmeters
- Conducted studies before and after cholinergic blockade and in dogs with heart failure.
- In normal dogs, ouabain caused increased mesenteric, renal, and iliac resistances initially; later, mesenteric resistance decreased while renal and iliac resistances remained high.
- After cholinergic blockade, mesenteric resistance increase was reversed, maintaining vasoconstriction.
- In dogs with heart failure, ouabain led to increased renal and iliac flow initially, shifting to vasodilatation while mesenteric resistance remained low throughout.
Structured PICO
Does intravenous ouabain alter regional hemodynamics in conscious dogs with and without experimental heart failure?
P
Population
14 conscious dogs, including 8 normal and 6 with experimental heart failure, evaluated for regional hemodynamic effects over 30 minutes.
I
Intervention
Intravenous ouabain (G-strophanthin) 20 µg/kg (and 5 µg/kg directly into mesenteric artery in a subset)
C
Comparator
Baseline (before ouabain administration) and comparison between normal and heart failure states
O
Outcome
Regional hemodynamic effects (blood flows and resistances in superior mesenteric, renal, and external iliac beds) over a 30-minute periodsurrogate
Ouabain causes direct vasoconstriction and cholinergically mediated mesenteric vasodilation in normal dogs, but reduces compensatory vasoconstriction by increasing blood flow to all beds in dogs with heart failure.
Cite This Study
Higgins et al. (1972) studied Experimental heart failure (n=14). Ouabain (G-strophanthin) vs. Baseline (before administration) was evaluated on Regional vascular resistance (superior mesenteric, renal, and external iliac beds). Intravenous ouabain causes regional vasoconstriction and mesenteric vasodilatation in normal dogs, but increases blood flow to all beds in dogs with experimental heart failure.