Role of endothelin in α-adrenoceptor coronary vasoconstriction

Mark W. Gorman, Martin Farias, Keith N. Richmond, Johnathan Tune, Eric O. Feigl

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

It has been proposed that α-adrenoceptor vasoconstriction in coronary resistance vessels results not from α-adrenoceptors on coronary smooth muscle but from α-adrenoceptors on cardiac myocytes that stimulate endothelin (ET) release. The present experiments tested the hypothesis that the α-adrenoceptor-mediated coronary vasoconstriction that normally occurs during exercise is due to endothelin. In conscious dogs (n = 10), the endothelin ETA/ETB receptor antagonist tezosentan (1 mg/kg iv) increased coronary venous oxygen tension at rest but not during treadmill exercise. This result indicates that basal endothelin levels produce a coronary vasoconstriction at rest that is not observed during the coronary vasodilation during exercise. In contrast, the α-adrenoceptor antagonist phentolamine increased coronary venous oxygen tension during exercise but not at rest. The difference between the endothelin blockade and α-adrenoceptor blockade results indicates that α-adrenoceptor coronary vasoconstriction during exercise is not due to endothelin. However, in anesthetized dogs, bolus intracoronary injections of the α-adrenoceptor agonist phenylephrine produced reductions in coronary blood flow that were partially antagonized by endothelin receptor blockade with tezosentan. These results are best explained if α-adrenoceptor-induced endothelin release requires high pharmacological concentrations of catecholamines that are not reached during exercise.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume288
Issue number4 57-4
DOIs
StatePublished - Apr 2005
Externally publishedYes

Fingerprint

Endothelins
Vasoconstriction
Adrenergic Receptors
Dogs
Oxygen
Endothelin Receptors
Phentolamine
Phenylephrine
Cardiac Myocytes
Vasodilation
Catecholamines
Smooth Muscle
Coronary Vessels
Pharmacology
Injections

Keywords

  • Coronary blood flow
  • Dogs
  • Exercise
  • Norepinephrine
  • Tezosentan

ASJC Scopus subject areas

  • Physiology

Cite this

Role of endothelin in α-adrenoceptor coronary vasoconstriction. / Gorman, Mark W.; Farias, Martin; Richmond, Keith N.; Tune, Johnathan; Feigl, Eric O.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 288, No. 4 57-4, 04.2005.

Research output: Contribution to journalArticle

Gorman, Mark W. ; Farias, Martin ; Richmond, Keith N. ; Tune, Johnathan ; Feigl, Eric O. / Role of endothelin in α-adrenoceptor coronary vasoconstriction. In: American Journal of Physiology - Heart and Circulatory Physiology. 2005 ; Vol. 288, No. 4 57-4.
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