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Updated: Jul 5, 2026

Assessing Endothelial Vasodilator Function with the Endo-PAT 2000
07:46

Assessing Endothelial Vasodilator Function with the Endo-PAT 2000

Published on: October 15, 2010

Diurnal variation in endothelium-dependent vasodilatation is not apparent in coronary artery disease

J A Shaw1, J P Chin-Dusting, B A Kingwell

  • 1Alfred and Baker Medical Unit, Alfred Hospital and Baker Medical Research Institute, Prahran, Victoria, Australia.

Circulation
|February 15, 2001
PubMed

Insights

Healthy individuals exhibit diurnal variation in endothelium-dependent vasodilation, a protective mechanism absent in coronary artery disease (CAD) patients. This loss of a protective endothelial function rhythm may contribute to increased morning acute coronary syndrome events in CAD.

Area of Science:

  • Cardiovascular Physiology
  • Endothelial Function
  • Chronobiology

Background:

  • Acute coronary syndromes (ACS) show a higher incidence in the morning (6 AM-12 PM).
  • Diurnal variation in endothelial function and its impairment in coronary artery disease (CAD) remain understudied.

Purpose of the Study:

  • To investigate diurnal variations in endothelial function.
  • To determine if this diurnal rhythm is altered in patients with coronary artery disease (CAD).

Main Methods:

  • Assessed forearm blood flow responses to acetylcholine, sodium nitroprusside, and N(G)-monomethyl-L-arginine via plethysmography in 10 CAD patients and 10 controls at 8 AM, 2 PM, and 8 PM.
  • Monitored heart rate, blood pressure, plasma cortisol, and inflammatory markers.

Main Results:

  • Control subjects displayed diurnal variation in sympathetic activity and basal forearm blood flow, with reduced flow at 8 PM.
  • Endothelium-dependent vasodilation to acetylcholine showed a diurnal pattern in controls (greater in the morning) but not in CAD patients.
  • Responses to sodium nitroprusside were consistent across time points and between groups.

Conclusions:

  • Normal volunteers possess a diurnal variation in endothelium-dependent vasodilation, potentially counteracting adverse diurnal hemodynamic changes.
  • Coronary artery disease patients demonstrated a loss of this protective endothelial function rhythm, which may be linked to increased morning ACS events.
Abstract

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