Publications (3)5.42 Total impact
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ABSTRACT: 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.
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ABSTRACT: We have previously reported on the positive effects of wild blueberries on arterial contractile response to alpha(1) adrenergic stimuli and on endothelium-mediated vasorelaxation. Our present study was designed to evaluate the effects of the dietary enrichment with wild blueberries on aortic function and reactivity in the developmental phase of essential hypertension in spontaneously hypertensive rats (SHR). We investigated the possible influence blueberries may have on the acetylcholine (Ach)-induced endothelium-dependent vasorelaxation and phenylephrine-induced vasoconstriction in young SHRs, as well as the contribution of the nitric oxide (NO) synthase and cyclooxygenase (COX) pathways in each of the above responses in an animal model with dysfunctional endothelium. Vascular ring studies were conducted in 3-mm isolated rat aortic ring preparations to investigate vasoconstriction induced by l-Phenylephrine (Phe, 10(-8) to 3x10(-6)M) and vasorelaxation induced by acetylcholine (Ach, 10(-9) to 3x10(-6)M). The major findings of our study were that in Phe-induced vasoconstriction, SHR-BB aortas relaxed to a greater degree in comparison to controls when mefenamic acid (MFA) was present and that the incubation with this COX inhibitor failed to restore - and in fact decreased - the maximum vasodilator response to Ach, in comparison to controls. Our vessel reactivity index (pD(2)) observations indicate that blueberries appear to modulate cell membrane-agonist (Ach) interactions primarily in response to Ach in the young SHR model, but not to the alpha(1) adrenoreceptor agonist. Incorporating wild blueberries in the diet seems to affect the endothelium-dependent vasorelaxation by modulating alternative metabolic pathway(s) (such as affecting the production/activity of COX-derived products) in the young SHR aorta.
University of Maine
Orono, Minnesota, United States
- Department of Food Science and Human Nutrition