Background: 

A lower incidence of cardiovascular diseases associates with moderate red wine consumption. This cardioprotective effect was mainly attributed to flavonoids, the non-alcoholic component of the red wine, whose intake inversely correlates with adverse cardiovascular events.

Aim: 

This study analysed whether two red wine flavonoids, Quercetin and Myricetin, directly affect mammalian myocardial and coronary function. The isolated and Langendorff perfused rat heart was used to test the cardiac influence of Quercetin and Myricetin under basal conditions. The intracellular signalling involved in the effects of these flavonoids was analysed on both isolated and perfused heart and by western blotting on cardiac and HUVEC extracts.

Results: 

Quercetin induced a biphasic effect represented by positive and negative inotropism and lusitropism at lower and higher concentrations, respectively. Contrarily, Myricetin dilates coronaries, with no effects on contractility and relaxation. Association of the two flavonoids dose-dependently induces vasodilation. Quercetin-induced positive inotropism and lusitropism depend on b1/b2 adrenergic receptors and associate with an increased intracellular cAMP content, while the negative inotropism and lusitropism observed at higher concentrations were a-adrenergic dependent. NOS inhibition abolished Myricetin-elicited vasodilation, also inducing Akt, ERK 1/2- and eNOS-phosphorylation in both cardiac ventricle and HUVEC. Myricetin-dependent vasodilation increases intracellular cGMP content and is abolished by PDEs inhibition.

Conclusions: 

The effects induced by Quercetin on basal mechanical performance and the selective vasodilation induced by Myricetin on the rat heart, point to these two flavonoids as potent cardiomodulators, potentially able to protect the heart in the presence of cardiovascular diseases.