[Vasomotricity of normal and atheromatous coronary arteries].
In order to fulfil, at any time, the myocardium requirements for oxygen and energy, the coronary circulation must be able of extremely intense and rapid vasodilation. This circulation undoubtedly is the body's regional circulation that "works" in the most difficult anatomical and physiological conditions. Coronary vasomotricity is regulated by three different systems operating synchronously. Metabolism-mediated vasodilatation, with adenosine as principal mediator, essentially concerns the small-caliber intramyocardial arterioles and is the predominant regulatory system in normal subjects. Nervous regulation (sympathetic and parasympathetic systems) exclusively concerns the wide, epicardial coronary arteries; it plays a modest, but non-negligible, role in normal subjects but becomes very important in patients with stenosis of the epicardial coronary arteries. Endothelium-mediated regulation, discovered about 10 years ago, seems to play a crucial role. Under the influence of haemodynamic and humoral stimuli, the endothelium synthesizes and releases substances which stimulate the underlying vascular smooth muscle. Nitric oxide (NO), or EDFR1, is the best known, but not the only messenger of vasodilatation; beside its relaxant effect on the smooth muscle, it exerts a potent platelet antiaggregating action. The functioning of these regulatory systems is deeply perturbed by atheroma of the coronary arteries: in addition to the fixed haemodynamic obstacle due to atheromatous stenosis, there is a diffuse decrease of endothelial functions and a rise in sensitivity to nervous vasoconstrictor stimuli.
Weber
S
S
Service de cardiologie, hôpital Cochin, Paris.
D000818:Animals; D003324:Coronary Artery Disease / Q000503:physiopathology*; D003331:Coronary Vessels / Q000502:physiology* / Q000503:physiopathology; D006801:Humans; D008722:Methods; D014661:Vasoconstriction / Q000502:physiology; D014664:Vasodilation / Q000502:physiology; D014666:Vasomotor System / Q000502:physiology* / Q000503:physiopathology
Vasomotricité des coronaires normales et athéromateuses.