Role of AMP-activated Protein Kinase in NO- and EDHF-mediated Endothelium-dependent Relaxations to Red Wine Polyphenols.

BACKGROUND: Several epidemiological studies have shown that regular consumption of moderate amounts of wine, in particular red wine, is associated with a decreased total mortality due, in part, to a reduced risk of cardiovascular diseases. The protective effect has been attributable to polyphenols, which are potent vasodilators and have anti-thrombotic properties. Polyphenols have been shown to induce pronounced endothelium-dependent relaxations of arteries by causing the redox-sensitive PI3-kinase-dependent formation of nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF). The aim of the present study was to determine the role of the AMP-activated protein kinase (AMPK) in the red wine polyphenols (RWPs)-induced endothelial formation of NO and EDHF.

METHODS AND RESULTS: Vascular reactivity was assessed in organ chambers. Cultured porcine coronary artery endothelial cells porcine coronary artery segements were used to study the phosphorylation level of endothelial NO synthase (eNOS) at serine 1177, and AMPK at the Threonine 172 by Western blot analysis and immunohistochemical staining. RWPs caused endothelium-dependent relaxations in rings from rat aorta and mesenteric artery, and in those from porcine coronary artery. NO-mediated relaxations to RWPs as assessed in the presence of indomethacin and charybdotoxin plus apamin, were inhibited by compound C (an inhibitor of AMPK). Compound C also reduced EDHF-mediated relaxations as assessed in the presence of indomethacin and N(G)-nitro L-arginine. In contrast, compound C did not affect endothelium-dependent relaxations to acetylcholine and those to sodium nitroprusside. Moreover, RWPs induced the phosphorylation of AMPK at threonine 172 and eNOS at serine 1177 in endothelial cells; these responses were inhibited by compound C.

CONCLUSION: The present findings indicate that RWPs cause both NO and EDHF-mediated relaxations in several types of isolated arteries and that these effects are dependent on the activation of the AMP-activated protein kinase pathway.