Vasoprotective effects

In the vasculature, ANG H not only increases contraction of smooth muscle cells, but is also able to induce vascular injury. This can be prevented by blocking NFkB activation [3] suggesting a link between ANG II and inflammation processes involved in the pathogenesis of arteriosclerosis (see below). Thus, ACE inhibitors not only decrease vascular tone but probably also exert vasoprotective effects. 

Alpha-glucosidase inhibitors (AGIs) were the first drags developed to meet the needs of better postprandial glucose control when sulfonylureas and biguanides were the only available oral antidiabetics that did not show any vasoprotective effect in the UGDP study [14]. 

Csiszar, A., Labinskyy, N., Podlutsky, A., Kaminski, P.M., et al. 2008. Vasoprotective effects of resveratrol and SlRTl attenuation of cigarette smoke-induced oxidative stress and proinflammatory phenotypic alterations. Am J Physiol Heart Circ Physiol. 294 H2721-H2735. 

One danger is that because herbal medications are not regulated, few if any clinical trials are performed even for safety or efficacy. One example is bilberry. Bilberry fruit is used to treat diabetes and diabetic retinopathy. Although animal models support the antioxidant role in vasoprotection, no well-designed and conducted clinical trials exist.The antioxidant effect may have benefit in AMD, as well. The antioxidant efficacy in bilberry is likely due to the tannin content, which is also found in grapes. 

Bilberry s ability to stimulate synthesis of connective tissue glycosami-noglycans may be the mechanism underlying its beneficial effects in several pathologies. Its gastroprotective, vasoprotective, and healing properties may all be tied to this action (5). 

The antioxidant actions of flavonoids appear to be involved in their observed antithrombotic action [50-52]. The antithrombotic and vasoprotective actions of quercetin, rutin, and other flavonoids have been attributed to their ability to bind to platelet membranes and scavenge free radicals [50]. In this manner, flavonoids restore the biosynthesis and action of endothelial prostacyclin and endothelialderived relaxing factor (EDRF), both of which are known to be inhibited by free radicals [50, 53, 54]. However, some flavonoids may inhibit arachidonic acid metabolism and platelet function by flavonoid-enzyme interactions rather than by antioxidant effects [55]. In addition to their antiaggregatory effects, flavonoids appear to increase vasodilation by inducing vascular smooth muscle relaxation, which may be mediated by inhibition of protein kinase C, PDFs, or by decreased cellular uptake of calcium [56]. 

Numerous studies indicate that regular intake of polyphenol-rich food and beverages such as red wine is associated with a protective effect on the cardiovascular system. In addition to the antioxidant property, polyphenols may also induce a beneficial effect on the cardiovascular system by several other mechanisms including the improvement of the vascular function. Indeed, experimental and chnical studies indicate that polyphenols are potent inducers of two major endothelial vasoprotective mechanisms, the formation of nitric oxide (NO) and the induction of endothelium-derived hyperpolarization (EDH). 

The endothelium plays a key role in the maintenance of vascular health, and the alteration of its function will promote the development of cardiovascular diseases. A large number of experimental and clinical studies indicate that polyphenols are potent activators of the endothehal cell leading to the formation of major vasoprotective factors including NO and EDH and that they contribute to delay the development of an endothehal dysfunction and to improve also an estabhshed endothelial dysfunction, in part, by reducing the vascular oxidative stress. AH these effects will contribute to a better perfusion of target organs and, hence, improve vascular health. 

Chaves AA, Joshi MS, Coyle CM, Brady JE, Dech SJ, Schanbacher BL, Baliga R, Basuray A, Bauer JA (2009) Vasoprotective endothelial effects of a standardized grape product in humans. Vascul Pharmacol 50(l-2) 20-26. doi 10.1016/j.vph.2008.08.004... 

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