O35 An anthocyanin-rich blackcurrant extract induced NO-mediated relaxation in coronary artery rings and eNOS phosphorylation in cultured endothelial cells: Role of sodium-glucose cotransporters 1 and 2

Introduction The beneficial cardiovascular effect of polyphenol-rich food and beverages has been attributed, at least in part, to an improved vascular function through an increased endothelial formation of nitric oxide (NO) and endothelium-dependent hyperpolarization (EDH), two major vasoprotective mechanisms. Black currant is a rich source of anthocyanins, and, in particular, of glucoside- and rutinoside-conjugated delphinidin and cyanidin. This study evaluated the role of sodium-glucose cotransporters (SGLT) 1 and 2 in the blackcurrant extract (BCE)-induced NO-mediated endothelium-dependent relaxation and activation of endothelial NO synthase (eNOS). Methods The reactivity of porcine coronary artery rings was assessed in organ chambers, and the expression and phosphorylation level of proteins in cultured porcine coronary artery endothelial cells by Western blot analysis. Results BCE (310.0 ± 0.1 mg gallic acid equivalent/g) was prepared from a blackcurrant juice containing 2.7 g gallic acid equivalent/L of polyphenols using a Sephadex LH-20 column. BCE caused potent concentration-dependent relaxations of coronary artery rings with endothelium, which were significantly reduced by the dual SGLT1 and SGLT2 inhibitor LX4211, and also to some extent by the SGLT2 inhibitor canagliflozin but not dapagliflozin. In contrast, LX4211 did not affect relaxations to bradykinin, sodium nitroprusside and epigallocatechin gallate. BCE induced the phosphorylation of eNOS at the activator site Ser1177 in cultured endothelial cells, which was significantly prevented by LX4211, dapagliflozin and canagliflozin. Conclusion These observations indicate that BCE is a potent activator of eNOS and inducer of NO-mediated vasorelaxation possibly subsequent to the entry of conjugated anthocyanins via SGLT1/2 into endothelial cells.