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Updated: May 12, 2026

Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research
08:42

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Published on: October 22, 2014

Sympathetic activation by sildenafil.

B G Phillips1, M Kato, C A Pesek

  • 1Division of Clinical and Administrative Pharmacy, Department of Internal Medicine, University of Iowa, Iowa City, USA.

Circulation
|January 11, 2000
PubMed
Summary
This summary is machine-generated.

Sildenafil significantly increases sympathetic nervous system activity at rest and during stress. This heightened sympathetic activation may be linked to cardiovascular events associated with sildenafil use.

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Area of Science:

  • Cardiovascular Physiology
  • Neuropharmacology

Background:

  • Sildenafil citrate is a common erectile dysfunction treatment.
  • Its effects on neural circulation and stress responses are not well understood.

Purpose of the Study:

  • To investigate the impact of sildenafil on the neural control of circulation.
  • To assess sildenafil's effects on neurocirculatory responses during stress.

Main Methods:

  • 14 healthy volunteers received 100 mg sildenafil or placebo in a double-blind crossover study.
  • Measurements included blood pressure, heart rate, forearm vascular resistance, muscle sympathetic nerve activity, and plasma catecholamines.
  • Responses to various physical and mental stressors were evaluated.

Main Results:

  • Sildenafil markedly increased muscle sympathetic nerve activity (141%) and plasma norepinephrine levels (31%) compared to placebo.
  • Sympathetic nerve traffic during stress was 2- to 8-fold higher after sildenafil.
  • Hemodynamic measures like blood pressure and heart rate remained similar between groups.

Conclusions:

  • Sildenafil induces significant sympathetic nervous system activation.
  • This activation occurs both at rest and during physiological stressors.
  • Findings suggest a potential mechanism for cardiovascular events linked to sildenafil use.