(–)-Epicatechin reduces blood pressure and improves vasorelaxation in spontaneously hypertensive rats by NO-mediated mechanism

Abstract

Studies in humans have found consumption of certain flavanoid-containing foods to be associated with improvement in endothelial function and with reduction of blood pressure (BP). (-)-Epicatechin is a compound representative of the flavanols (a subfamily of flavonoids), abundant in cocoa seeds, which is preserved during the industrialization process to chocolate. The antihypertensive effect of dietary (-)-epicatechin was investigated on spontaneously hypertensive rats (SHR). Consumption of (-)-epicatechin-supplemented diet (3 g (-)-epicatechin/kg diet) decreased blood pressu re (BP) in SHR by 27 and 23 mm of Hg on days 2 and 6, respectively. On day 6,a 173% increase of nitric oxide (NO) synthase activity was observed in the aorta of EPI-SHR as compared to non-supplemented SHR (p<0.05). Responses to acetylcholine (ACh) were then examined in femoral arteries in the absence and the presence of with L-NAME, a non-selective NOS inhibitor, to assess the Ach-mediated relaxation ascribed to NO-dependent and independent mechanisms Acetylcholine-induced endothelium-dependent relaxation in the femoral artery was significantly higher in EPI-SHR than in SHR, with a predominance of the NO-dependent component of this relaxation. The endothelium-independent relaxation, assayed by using the NO donor sodium nitroprusside (SNP), resulted non significant different in the three experimental groups, demonstrating an unaffected function of vascular smooth muscle cells. These results give further support to the concept that (-)-epicatechin can modulate BP in hypertension by increasing NO levels in the vasculature.