Attenuation of alpha-adrenergic-induced vasoconstriction by dietary wild blueberries (Vaccinium angustifolium) is mediated by the NO-cGMP pathway in spontaneously hypertensive rats (SHRs)

AbstractThe role of wild blueberries (WB) on key signaling steps of nitric oxide (NO) and cyclooxygenase (COX) pathways was examined in spontaneously hypertensive rats (SHRs) after eight weeks on a control (C) or an 8% w/w WB diet. Aortic rings from SHRs were stimulated with phenylephrine (Phe) in the absence or presence of inhibitors of: soluble guanylyl cyclase (sGC), phosphodiesterase-5 (PDE5), prostaglandin I2 (PGI2) synthase and thromboxane A2 (TXA2) synthase. Additionally, enzymatic activities in these pathways were determined by the concentration of NO, cyclic guanosine monophosphate (cGMP), PGI2 and TXA2. In the WB-fed SHR, attenuation of Phe-induced vasoconstriction was mediated by an increased synthesis or preservation of cGMP. Despite an increased release of PGI2 in the WB group, neither inhibition of PGI2 or TXA2 synthase resulted in a different response to Phe between the control and the WB rings. Hence, in the SHR, WB decrease Phe-mediated vasoconstriction under basal conditions by enhancing...