摘要：It is well established in experimental animals and Humans that endothelial cells,which cover the luminal surface of all blood vessels,have a pivotal role in the control of vascular homeostasis.The protective effect of endothelial cells is mostly due to their ability to respond to circulating hormones,autacoids,blood-and platelet-derived factors,and also to blood flow by inducing potent vasoprotectivemechanismsincluding predominantlythe formation of nitric oxide(NO),and,often also to some extent,endothelium-derived hyperpolarization,and prostacyclin(PGI2).Besides being a potent vasodilator,NO also effectively prevents platelet activation and has anti-thrombotic and anti-atherosclerotic properties.An endothelial dysfunction characterized by a reduced generation of these endothelium-dependent vasodilator mechanisms associated with vascular oxidative stress and the formation of endothelium-derived contracting factors such as contractile prostanoids is often observed in most types of cardiovascular diseases including hypertension,hypercho⁃lesterolemia,diabetes,and also during physiological ageing in both experimental animals and Humans.Nutrition-derived polyphenols such as those from grapes,tea,cocoa,and berries have been shown to stimulate the endothelial formation of NO by activating the Src/PI3-kinase/Akt-dependent phosphorylation of endothelial NO synthase(eNOS)and to enhance eNOS expression.As a consequence,the active polyphenols will promote a sustained forma⁃tion of NO that contributes to protect the vascular system.Polyphenol-rich products have also been shown to improve an established endothelial dysfunction and to delay the onset of the induction of an endothelial dysfunction in several experimental models of cardiovascular diseases including hypertension and in ageing.Moreover,endothelial senescence characterized by cell cycle arrest and the acquisition of a pro-inflammatory and pro-atherothrombotic phenotype has been identified as an early event promotingthe development of endothelial dysfunc⁃tion.Pr
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