title: Reprint of: 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. This article is part of a Special Issue entitled "Coronary Blood Flow".
authors.affiliation: Institut für Pathophysiologie, Universitätsklinikum Essen, Hufelandstr. 55, 45122 Essen, Germany. gerd.heusch@uk-essen.de
authors.forename: Gerd
authors.initials: G
authors.lastname: Heusch