NAD(P)H oxidase-derived peroxide mediates elevated basal and impaired flow-induced NO production in SHR mesenteric arteries in vivo

Xiaosun Zhou, H. Glenn Bohlen, Steven J. Miller, Joseph L. Unthank

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45 Scopus citations

Abstract

Nitric oxide (NO) and reactive oxygen species (ROS) have fundamentally important roles in the regulation of vascular tone and remodeling. Although arterial disease and endothelial dysfunction alter NO and ROS levels to impact vasodilation and vascular structure, direct measurements of these reactive species under in vivo conditions with flow alterations are unavailable. In this study, in vivo measurements of NO and H2O2 were made on mesenteric arteries to determine whether antioxidant therapies could restore normal NO production in spontaneously hypertensive rats (SHR). Flow was altered from ∼50-200% of control in anesthetized Wistar-Kyoto rats (WKY) and SHR by selective placement of microvascular clamps on adjacent arteries while NO and H2O2 were directly measured with microelectrodes. Relative to WKY, SHR had significantly increased baseline NO and H2O 2 concentrations (2,572 ± 241 vs. 1,059 ± 160 nM, P < 0.01; and 26 ± 7 vs. 7 ± 1 μM, P < 0.05, respectively). With flow elevation, H2O2 but not NO increased in SHR; NO but not H2O2 was elevated in WKY. Apocynin and polyethylene-glycolated catalase decreased baseline SHR NO and H 2O2 to WKY levels and restored flow-mediated NO production. Suppression of NAD(P)H oxidase with gp91ds-tat decreased SHR H 2O2 to WKY levels. Addition of topical H2O 2 to increase peroxide to the basal concentration measured in SHR elevated WKY NO to levels observed in SHR. The results support the hypothesis that increased vascular peroxide in SHR is primarily derived from NAD(P)H oxidase and increases NO concentration to levels that cannot be further elevated with increased flow. Short-term and even acute administration of antioxidants are able to restore normal flow-mediated NO signaling in young SHR.

Original languageEnglish (US)
Pages (from-to)H1008-H1016
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume295
Issue number3
DOIs
StatePublished - Sep 1 2008

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Keywords

  • Flow mediated
  • Hypertension
  • NAD(P)H oxidase inhibition
  • Oxidative stress
  • Spontaneously hypertensive rats

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine

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