Impaired Vasodilation in the Pathogenesis of Hypertension: Focus on Nitric Oxide, Endothelial-Derived Hyperpolarizing Factors, and Prostaglandins

Authors

  • Thomas D. Giles MD,

    1. From the Heart & Vascular Institute, Tulane University Medical Center ; 1the Department of Anesthesiology, Ochsner Medical Center ; 2 and the Department of Pharmacology, Tulane University Medical Center,3 New Orleans, LA
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  • 1 Gary E. Sander MD, PhD,

    1. From the Heart & Vascular Institute, Tulane University Medical Center ; 1the Department of Anesthesiology, Ochsner Medical Center ; 2 and the Department of Pharmacology, Tulane University Medical Center,3 New Orleans, LA
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  • 1 Bobby D. Nossaman MD,

    1. From the Heart & Vascular Institute, Tulane University Medical Center ; 1the Department of Anesthesiology, Ochsner Medical Center ; 2 and the Department of Pharmacology, Tulane University Medical Center,3 New Orleans, LA
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  • and 2 Philip J. Kadowitz PhD 2

    1. From the Heart & Vascular Institute, Tulane University Medical Center ; 1the Department of Anesthesiology, Ochsner Medical Center ; 2 and the Department of Pharmacology, Tulane University Medical Center,3 New Orleans, LA
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Thomas D. Giles, MD, Professor of Medicine, Department of Medicine, Tulane University School of Medicine, 109 Holly Drive, Metairie, LA 70005
E-mail: tgiles4@cox.net

Abstract

J Clin Hypertens (Greenwich). 2012;14:198–205. ©2012 Wiley Periodicals, Inc.

Under resting conditions the arterial vasculature exists in a vasoconstricted state referred to as vascular tone. Physiological dilatation in response to increased flow, a function of normal endothelium is necessary to maintain normal blood pressure. Endothelial dysfunction in vascular smooth muscle cells thus results in loss of normal vasorelaxant function and the inability of arteries to appropriately dilate in response to increased blood flow in either a systemic or regional vascular bed, resulting in increased blood pressure, a sequence that may represent a common pathway to hypertension. Normal vasorelaxation is mediated by a number of endothelial systems including nitric oxide (NO), prostaglandins (PGI2 and PGE2), and a family of endothelial-derived hyperpolarizing factors (EDHF). In response to hemodynamic shear stress, endothelium continuously releases NO, EDHF, and PGI2 to provide vasodilatation. EDHF, not a single molecule but rather a group of molecules that includes epoxyeicosatrienoic acids, hydrogen peroxide, carbon monoxide, hydrogen sulfide, C-natriuretic peptide, and K+ itself, causes vasodilatation by activation of vascular smooth muscle cell K+ channels, resulting in hyperpolarization and thus vasorelaxation. The understanding and effective management of blood pressure requires an understanding of both physiologic and pathophysiologic regulation of vascular tone. This review describes molecular mechanisms underlying normal endothelial regulation and pathological states, such as increased oxidative stress, which cause loss of vasorelaxation. Possible pharmacological interventions to restore normal function are suggested.

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