Regulation of vascular tone by plant polyphenols: role of nitric oxide

Vascular endothelium plays a crucial role in regulating blood flow and vascular tone. It can synthesize and release different relaxant factors including nitric oxide (NO). This article summarizes pharmacological properties of red wine polyphenol extracts (RWPC) with respect to endothelial NO. It is shown that RWPC produces endothelium-dependent relaxation as a result of enhanced NO synthesis rather than enhanced biological activity of NO or protection against breakdown by O2-. The mechanisms involve influx of Ca2+ and production of O2- within the endothelial cells. These results suggest that RWPC, by releasing endothelial NO, may have therapeutically relevant effects against cardiovascular diseases.