Endothelium-dependent contractions: when a good guy turns bad!
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.
Vanhoutte
Paul M
PM
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
Tang
Eva H C
EH
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*
D016232:Endothelins; D017382:Reactive Oxygen Species; D017482:Receptors, Thromboxane; D009569:Nitric Oxide