C-reactive protein does not relax vascular smooth muscle: Effects mediated by sodium azide in commercially available preparations

Albert N. Swafford, Ian N. Bratz, Jarrod D. Knudson, Paul A. Rogers, Jennifer M. Timmerman, Johnathan Tune, Gregory M. Dick

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

C-reactive protein (CRP), an acute-phase protein and newly recognized indicator of cardiovascular risk, may have direct actions on the vascular wall. Previous studies suggest that CRP is a vasodilator that activates smooth muscle K+ channels. We examined the reported vasoactive properties of CRP and further explored its mechanisms of action. CRP decreased blood pressure in rats and increased coronary flow in open-chest dogs at a constant coronary perfusion pressure. CRP relaxed rat aortic rings and mesenteric small arteries that were contracted with phenylephrine. Relaxation was not affected by endothelial denudation or inhibition of nitric oxide (NO) synthase but was blocked by inhibition of soluble guanylate cyclase or K+ channels. CRP solutions remained effective, i.e., elicited vasodilation, even after boiling or enzymatic digestion, which suggests the presence of a nonprotein contaminant. Sodium azide (NaN3, 0.1%) is the preservative used for commercially available CRP and a potential source of NO. NaN3 elicited the same cardiovascular effects as CRP preparations at equal concentrations, and its actions were blocked by inhibition of guanylate cyclase and K+ channels. NaN3-free CRP, prepared by gel-filtration centrifugation and confirmed by electrophoresis, had no effect on vascular tone. Inhibition of vascular smooth muscle catalase with 3-amino-1,2,4-triazole completely prevented the effects of NaN3 and NaN3- containing CRP solutions. We demonstrate that the acute vasoactive properties of commercially available CRP preparations are attributable to NaN3 (and subsequent production of NO by catalase); therefore, this study suggests a reappraisal of the acute role of CRP in regulating vascular tone.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume288
Issue number4 57-4
DOIs
StatePublished - Apr 2005
Externally publishedYes

Fingerprint

Sodium Azide
Vascular Smooth Muscle
C-Reactive Protein
Blood Vessels
Catalase
Nitric Oxide
Amitrole
Mesenteric Arteries
Acute-Phase Proteins
Guanylate Cyclase
Phenylephrine
Vasodilator Agents
Centrifugation
Vasodilation
Nitric Oxide Synthase
Gel Chromatography
Smooth Muscle
Electrophoresis
Digestion
Thorax

Keywords

  • Catalase
  • Guanosine 3′,5′-cyclic monophosphate
  • Nitric oxide
  • Potassium channel
  • Soluble guanylate cyclase

ASJC Scopus subject areas

  • Physiology

Cite this

C-reactive protein does not relax vascular smooth muscle : Effects mediated by sodium azide in commercially available preparations. / Swafford, Albert N.; Bratz, Ian N.; Knudson, Jarrod D.; Rogers, Paul A.; Timmerman, Jennifer M.; Tune, Johnathan; Dick, Gregory M.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 288, No. 4 57-4, 04.2005.

Research output: Contribution to journalArticle

Swafford, Albert N. ; Bratz, Ian N. ; Knudson, Jarrod D. ; Rogers, Paul A. ; Timmerman, Jennifer M. ; Tune, Johnathan ; Dick, Gregory M. / C-reactive protein does not relax vascular smooth muscle : Effects mediated by sodium azide in commercially available preparations. In: American Journal of Physiology - Heart and Circulatory Physiology. 2005 ; Vol. 288, No. 4 57-4.
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AU - Swafford, Albert N.

AU - Bratz, Ian N.

AU - Knudson, Jarrod D.

AU - Rogers, Paul A.

AU - Timmerman, Jennifer M.

AU - Tune, Johnathan

AU - Dick, Gregory M.

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N2 - C-reactive protein (CRP), an acute-phase protein and newly recognized indicator of cardiovascular risk, may have direct actions on the vascular wall. Previous studies suggest that CRP is a vasodilator that activates smooth muscle K+ channels. We examined the reported vasoactive properties of CRP and further explored its mechanisms of action. CRP decreased blood pressure in rats and increased coronary flow in open-chest dogs at a constant coronary perfusion pressure. CRP relaxed rat aortic rings and mesenteric small arteries that were contracted with phenylephrine. Relaxation was not affected by endothelial denudation or inhibition of nitric oxide (NO) synthase but was blocked by inhibition of soluble guanylate cyclase or K+ channels. CRP solutions remained effective, i.e., elicited vasodilation, even after boiling or enzymatic digestion, which suggests the presence of a nonprotein contaminant. Sodium azide (NaN3, 0.1%) is the preservative used for commercially available CRP and a potential source of NO. NaN3 elicited the same cardiovascular effects as CRP preparations at equal concentrations, and its actions were blocked by inhibition of guanylate cyclase and K+ channels. NaN3-free CRP, prepared by gel-filtration centrifugation and confirmed by electrophoresis, had no effect on vascular tone. Inhibition of vascular smooth muscle catalase with 3-amino-1,2,4-triazole completely prevented the effects of NaN3 and NaN3- containing CRP solutions. We demonstrate that the acute vasoactive properties of commercially available CRP preparations are attributable to NaN3 (and subsequent production of NO by catalase); therefore, this study suggests a reappraisal of the acute role of CRP in regulating vascular tone.

AB - C-reactive protein (CRP), an acute-phase protein and newly recognized indicator of cardiovascular risk, may have direct actions on the vascular wall. Previous studies suggest that CRP is a vasodilator that activates smooth muscle K+ channels. We examined the reported vasoactive properties of CRP and further explored its mechanisms of action. CRP decreased blood pressure in rats and increased coronary flow in open-chest dogs at a constant coronary perfusion pressure. CRP relaxed rat aortic rings and mesenteric small arteries that were contracted with phenylephrine. Relaxation was not affected by endothelial denudation or inhibition of nitric oxide (NO) synthase but was blocked by inhibition of soluble guanylate cyclase or K+ channels. CRP solutions remained effective, i.e., elicited vasodilation, even after boiling or enzymatic digestion, which suggests the presence of a nonprotein contaminant. Sodium azide (NaN3, 0.1%) is the preservative used for commercially available CRP and a potential source of NO. NaN3 elicited the same cardiovascular effects as CRP preparations at equal concentrations, and its actions were blocked by inhibition of guanylate cyclase and K+ channels. NaN3-free CRP, prepared by gel-filtration centrifugation and confirmed by electrophoresis, had no effect on vascular tone. Inhibition of vascular smooth muscle catalase with 3-amino-1,2,4-triazole completely prevented the effects of NaN3 and NaN3- containing CRP solutions. We demonstrate that the acute vasoactive properties of commercially available CRP preparations are attributable to NaN3 (and subsequent production of NO by catalase); therefore, this study suggests a reappraisal of the acute role of CRP in regulating vascular tone.

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