اثرات عروقي وابسته و غيروابسته به اندوتليوم فلاونوييد كويرستين در آيورت سينه اي موش صحرايي ديابتي

Endothelium-dependent and -independent vascular effect of the flavonoid quercetin in thoracic aorta of diabetic rats

Introduction: Quercetin is one of the most common forms of flavonoids in foodstuffs, which could have multiple beneficial effects on the cardiovascular system including an induction of vasorelaxation in conductance and resistive vessels. Due to changes in endothelial functionality in diabetes mellitus, there is an enhanced vascular responsiveness to contractile agonists. Therefore, the role ofendothelium was evaluated in vasorelaxant effect of quercetin in diabetic rats. Materials and Methods: For this purpose, male Wistar rats were divided into control and diabetic groups. For induction of diabetes, streptozotocin (60 mg/Kg, i.p.) was used. The body weight and serum glucose parameters were determined before and at 2nd and 4th after the experiment. Contractile responsiveness to KCI and noreadrenalin (NA) and quercetin-induced vasorelaxation were measured at the end of study. Results: After 4 weeks, quercetin (I mM-10 mM) induced a dose-dependent vasorelaxation in aortic rings precontracted with KCI and\or NA from both control and diabetic groups (p<0.01). Furthermore, this vasorelaxation was significantly attenuated after endothelium removal and at higher concentrations of quercetin (> 0.5 and 5 mM for NA and KCI respectively), this vasorelaxation was endothelium-independent. Conclusion: It can be concluded that the flavonoid quercetin exerts endothelium-dependent and -independent effects, and this response depends on flavonoid concentration.