title: The paradox of α-adrenergic coronary vasoconstriction revisited.
abstract: Activation of coronary vascular α-adrenoceptors results in vasoconstriction which competes with metabolic vasodilation during sympathetic activation. Epicardial conduit vessel constriction is largely mediated by α(1)-adrenoceptors; the constriction of the resistive microcirculation largely by α(2)-adrenoceptors, but also by α(1)-adrenoceptors. There is no firm evidence that α-adrenergic coronary vasoconstriction exerts a beneficial effect on transmural blood flow distribution. In fact, α-blockade in anesthetized and conscious dogs improves blood flow to all transmural layers, during normoperfusion and hypoperfusion. Also, in patients with coronary artery disease, blockade of α(1)- and α(2)-adrenoceptors improves coronary blood flow, myocardial function and metabolism.
authors: Institut für Pathophysiologie, Universitätsklinikum Essen, Hufelandstr. 55, 45122 Essen, Germany. gerd.heusch@uk-essen.de
authors: Gerd
authors: G
authors: Heusch
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000378:metabolism; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism; D000818:Animals; D003324:Coronary Artery Disease; D003326:Coronary Circulation / Q000502:physiology*; D003327:Coronary Disease / Q000503:physiopathology; D003331:Coronary Vessels / Q000378:metabolism; D004285:Dogs; D006321:Heart / Q000503:physiopathology; D006801:Humans; D007511:Ischemia; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D014661:Vasoconstriction / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology
chemical_list: D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha