Vascular Reactivity Is Affected by Dietary Consumption of Wild Blueberries in the Sprague-Dawley Rat

We have previously reported that consumption of blueberry-enriched (BB) diets attenuates the arterial contractile response to alpha(1)-adrenergic stimuli and affects vasomotor tone via endothelium-related pathways. The present study was designed to evaluate vascular function and responsiveness in aortas of weanling male Sprague-Dawley rats fed a control (C) or a BB diet for 7 weeks. Vascular ring studies were conducted in 3-mm isolated rat aortic ring preparations to investigate vasoconstriction induced by L-phenylephrine (Phe) (10(-8)-3 x 10(-6) M) and vasorelaxation induced by acetylcholine (ACh) (10(-8)-3 x 10(-6) M). Agonists were used alone and in the presence of nitric oxide (NO) synthase and cyclooxygenase (COX) inhibitors. We observed a significantly diminished vasoconstrictor response to Phe in aortic rings from rats fed the BB diet. Inhibition of NO synthase but not COX caused a significant increase in the constrictor response in both dietary groups, with the BB group having the greater response. Similarly, the participation of the NO pathway in endothelium-dependent vasorelaxation induced by ACh was greater in the rats fed a BB diet, while COX inhibition showed no effect on maximum ACh-induced vasorelaxation in any diet group. The vessel sensitivity of BB aortic rings to the vasoconstrictor and vasodilator was significantly reduced when compared to controls. We have concluded that diets enriched with blueberries, fed for 7 weeks in Sprague-Dawley rats, seem to affect NO metabolic pathways in the aorta at basal and stimulated levels.