Endothelial adrenoceptors.
alpha2 -Adrenergic agonists cause endothelium-dependent relaxation in a number of isolated blood vessels. This effect is explained by the activation of endothelial alpha 2 -adrenoceptors linked to nitric oxide synthase by G i -coupling proteins. The endothelial response to alpha 2 -adrenergic agonists is blunted considerably after regeneration of the endothelium and in atherosclerotic arteries. The relaxation of isolated arteries caused by beta-adrenergic agonists is reduced by removal of the endothelium and, in most cases, by inhibitors of the l -arginine nitric oxide pathway. Likewise, in the intact animal and in the human forearm the vasodilatation to beta 2 -adrenergic agonists is blunted by inhibitors of nitric oxide synthase. Whether these findings reflect the presence of functional beta-adrenoceptors on the endothelium remains controversial. Several beta-adrenergic blockers cause endothelium-dependent relaxation in vitro or augment the production of nitric oxide in vivo. However, these responses cannot be attributed to interactions with endothelial beta-adrenoceptors.
Vanhoutte
P M
PM
Institut de Recherches Internationales Servier, Courbevoie, France.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D012898:Autacoids / Q000494:pharmacology; D001578:Benzopyrans / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D004983:Ethanolamines / Q000494:pharmacology; D006801:Humans; D008956:Models, Chemical; D000068577:Nebivolol; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010656:Phenylephrine / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000187:drug effects / Q000378:metabolism*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D012898:Autacoids; D001578:Benzopyrans; D004983:Ethanolamines; D011941:Receptors, Adrenergic; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D000068577:Nebivolol; D010656:Phenylephrine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase