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Effects of infusing alpha-atrial natriuretic peptide in primary hypertension during converting enzyme inhibition
E Agabiti-Rosei1, M Castellano, M Beschi
1Department of Medical Sciences, University of Brescia, Italy.
Insights
Converting enzyme inhibition enhances the natriuretic and diuretic effects of atrial natriuretic peptide (ANP) in hypertensive patients. This suggests a potential synergistic action between these treatments for managing blood pressure.
Area of Science:
- Cardiology
- Nephrology
- Pharmacology
Background:
- Atrial natriuretic peptide (ANP) plays a role in regulating blood pressure and fluid balance.
- Converting enzyme (CE) inhibitors are commonly used antihypertensive medications.
Purpose of the Study:
- To investigate the combined effects of ANP and CE inhibition on hypertensive patients.
- To determine if CE inhibition potentiates the natriuretic and diuretic actions of ANP.
Main Methods:
- A placebo-controlled, single-blind, randomized study involving six primary hypertensive patients.
- Patients received intravenous infusions of placebo, ANP alone, or ANP after enalapril (CE inhibitor).
- Measurements included blood pressure, heart rate, echocardiography, plasma renin activity, and urinary excretion of electrolytes and catecholamines.
Main Results:
- ANP infusion increased urinary sodium and volume excretion, and urinary catecholamines.
- Enalapril significantly reduced blood pressure in all patients.
- ANP infusion during CE inhibition resulted in a more sustained increase in sodium excretion and diuresis compared to ANP alone.
- CE inhibition reduced plasma renin activity without further blood pressure reduction.
Conclusions:
- CE inhibition may enhance the natriuretic and diuretic effects of ANP in hypertensive individuals.
- The combination of CE inhibition and ANP may offer a synergistic approach to managing hypertension.
- Further research is warranted to explore the clinical implications of this interaction.
Abstract:
The effect of atrial natriuretic peptide (ANP), before and after converting enzyme (CE) inhibition, was investigated in six primary hypertensive patients taking a constant diet. In this placebo-controlled, single-blind, randomized study, the patients received, on three different days, i.v. infusions of (a) placebo, or (b) alpha-human ANP, 150 micrograms over 30 min, or (c) alpha-human ANP after acute CE inhibition by enalapril (EN) 20 mg P.O., 4 h before ANP infusion. ANP infusion increased urinary sodium (p less than 0.001) and volume excretion. Blood pressure (BP), heart rate, stroke volume and shortening fraction (echocardiography), plasma renin activity (PRA), and plasma aldosterone did not change significantly. Urinary norepinephrine and dopamine were significantly increased (p less than 0.05) after ANP infusion. BP was significantly reduced after EN in every patient (p less than 0.05). ANP infusion during CE inhibition induced a more sustained increase of sodium excretion and diuresis with respect to ANP infusion alone (p less than 0.05). PRA was significantly reduced while no further reduction of BP was observed. These data suggest that CE inhibition may increase the natriuretic and diuretic effect of ANP in hypertensive patients.