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Chronic ouabain infusion does not cause hypertension in sheep
G B Pidgeon1, A M Richards, M G Nicholls
1Department of Nephrology, Christchurch Hospital, New Zealand.
The American Journal of Physiology
|March 1, 1996
Summary
Chronic high-dose ouabain infusion in sheep did not raise arterial pressure. This study found ouabain to be antidiuretic and antinatriuretic, with minor effects on vasoactive hormones.
Area of Science:
- Cardiovascular Physiology
- Endocrinology
Background:
- Ouabain, a cardiac glycoside, is proposed as an adrenal hormone that elevates arterial pressure.
- Its precise physiological role and effects in mammals require further elucidation.
Purpose of the Study:
- To investigate the chronic effects of ouabain infusion on blood pressure, urine electrolytes, and vasoactive hormones in conscious sheep.
- To determine if ouabain alters pressor responsiveness to angiotensin II.
Main Methods:
- Eight healthy ewes received daily ouabain infusions (0.25 mg) for 22 days under controlled dietary sodium and potassium intake.
- Measurements included arterial pressure, heart rate, urine electrolytes, and plasma levels of renin, angiotensin II, aldosterone, and cortisol.
Main Results:
- Ouabain infusion reduced heart rate and arterial pressure.
- It caused significant decreases in urine volume and sodium excretion.
- Plasma renin and angiotensin II levels decreased, while aldosterone and cortisol levels increased slightly.
Conclusions:
- High-dose chronic ouabain administration in sheep does not elevate arterial pressure or enhance pressor response to angiotensin II.
- Ouabain exhibits antidiuretic and antinatriuretic properties.
- It induces minor alterations in the renin-angiotensin-aldosterone system and cortisol levels.