Title: Noradrenergic Vascular Hyper-Responsiveness in Human Hypertension Is Dependent on Oxygen Free Radical Impairment of Nitric Oxide Activity
Abstract: Background—Noradrenergic vascular hyper-responsiveness is a hallmark of essential hypertension. To evaluate whether nitric oxide plays a role in the enhanced vascular response to norepinephrine in hypertension, we examined 32 hypertensives and 28 normotensives who were distributed in 3 experimental series. Methods and Results—In the first series, we measured the forearm blood flow (FBF) response to a norepinephrine infusion under control conditions and during the infusion of l-N-monomethylarginine (L-NMMA). Norepinephrine evoked dose-dependent vasoconstriction that was greater in hypertensives than in normotensives (maximum FBF, −61±1 versus −51±1%; P<0.01). During L-NMMA infusion, norepinephrine vasoconstriction was not modified in hypertensives; however, it was potentiated in normotensives (maximum FBF, −64±2%; P<0.01). In the second series, we tested whether norepinephrine vasoconstriction could be affected by an antioxidant such as ascorbic acid. Norepinephrine vasoconstriction was blunted by ascorbic...
Publication Year: 2000
Publication Date: 2000-08-01
Language: en
Type: article
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