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alpha-adrenergic coronary vasoconstriction and myocardial ischemia in humans

G Heusch1, D Baumgart, P Camici

  • 1Abteilung für Pathophysiologie and Abteilung für Kardiologie, Universitätsklinikum Essen, Essen, Germany. gerd.heusch@uni-essen.de

Circulation
|February 15, 2000
PubMed

Insights

Alpha-adrenergic coronary constriction is not present at rest but is amplified in conditions like endothelial dysfunction and atherosclerosis. This amplified constriction can cause myocardial ischemia and impair heart function.

Area of Science:

  • Cardiology
  • Pharmacology
  • Physiology

Background:

  • Alpha-adrenergic coronary vasomotion is crucial for regulating blood flow to the heart.
  • Previous studies in animals suggested a role for alpha-adrenergic receptors in coronary arteries.

Purpose of the Study:

  • To investigate alpha-adrenergic coronary vasomotion in humans.
  • To determine the role of alpha-adrenoceptor activation in coronary endothelial dysfunction and atherosclerosis.

Main Methods:

  • Quantitative coronary angiography
  • Doppler measurements
  • Positron Emission Tomography (PET)

Main Results:

  • No evidence of alpha-adrenergic coronary constrictor tone at rest in humans.
  • Alpha-adrenoceptor activation significantly augmented coronary constriction in the presence of endothelial dysfunction and atherosclerosis.
  • Both alpha(1)- and alpha(2)-adrenoceptors in epicardial arteries and microvessels were involved.
  • Augmented constriction occurred during exercise and interventions, leading to myocardial ischemia and reduced cardiac function.
  • Recent findings suggest a genetic influence on alpha(2)-adrenergic coronary constriction.

Conclusions:

  • Alpha-adrenergic coronary constriction is not a factor at rest but becomes significant under pathological conditions.
  • Endothelial dysfunction and atherosclerosis enhance alpha-adrenergic responses, potentially causing ischemia.
  • Alpha-adrenergic pathways, particularly involving alpha(2) receptors, are key targets for understanding and managing coronary artery disease.

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