title: Endothelium-dependent contractions: when a good guy turns bad!
abstract: Endothelial cells can induce contractions of the underlying vascular smooth muscle by generating vasoconstrictor prostanoids (endothelium-dependent contracting factor; EDCF). The endothelial COX-1 isoform of cyclooxygenase appears to play the dominant role in the phenomenon. Its activation requires an increase in intracellular Ca(2+) concentration. The production of EDCF is inhibited acutely and chronically by nitric oxide (NO), and possibly by endothelium-dependent hyperpolarizing factor (EDHF). The main prostanoids involved in endothelium-dependent contractions appear to be endoperoxides (PGH(2)) and prostacyclin, which activate thromboxane-prostanoid (TP) receptors of the vascular smooth muscle cells. Oxygen-derived free radicals can facilitate the production and/or the action of EDCF. Endothelium-dependent contractions are exacerbated by ageing, obesity, hypertension and diabetes, and thus are likely to contribute to the endothelial dysfunction observed in older people and in essential hypertensive patients.
authors.affiliation: Department of Pharmacology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong SAR, China. vanhoutt@hkucc.hku.hk
authors.forename: Paul M
authors.initials: PM
authors.lastname: Vanhoutte
authors.forename: Eva H C
authors.initials: EH
authors.lastname: Tang
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D020013:Calcium Signaling; D016232:Endothelins / Q000502:physiology; D004730:Endothelium, Vascular / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D009569:Nitric Oxide / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D017482:Receptors, Thromboxane / Q000502:physiology; D014652:Vascular Diseases / Q000503:physiopathology; D014661:Vasoconstriction / Q000502:physiology*
chemical_list: D016232:Endothelins; D017382:Reactive Oxygen Species; D017482:Receptors, Thromboxane; D009569:Nitric Oxide