Activation of hexosamine pathway impairs nitric oxide (NO)-dependent arteriolar dilations by increased protein O-GlcNAcylation

Timea Beleznai, Zsolt Bagi

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

We hypothesized that under high glucose conditions, activation of the hexosamine pathway leads to impaired nitric oxide (NO)-dependent arteriolar dilation. Skeletal muscle arterioles (diameter: ~160μm) isolated from male Wistar rats were exposed to normal glucose (NG, 5.5mmol/L) or high glucose concentrations (HG, 30mmol/L, for 2h) and agonist-induced diameter changes were measured with videomicroscopy. Western blots were performed to identify the vascular levels of protein O-linked-N-acetyl-glucosamine (O-GlcNAc) and phosphorylated endothelial NO synthase (eNOS). In arterioles exposed to HG, dilations to histamine were abolished compared to those exposed to NG (max: -6±6% and 69±9%, respectively), while acetylcholine-induced responses were not affected. Inhibition of NO synthesis with N G-nitro-l-arginine methyl ester (L-NAME) reduced histamine-induced dilations in NG arterioles, but it had no effect on microvessels exposed to HG. Dilations to the NO donor, sodium nitroprusside and constrictions to norepinephrine and serotonin were similar in the two groups. In the presence of the inhibitor of hexosamine pathway, azaserine, histamine-induced dilations were significantly augmented in arterioles exposed to HG (max: 67±2%). Moreover, exposure of vessels to glucosamine (5mmol/L, for 2h) resulted in reduced histamine-induced arteriolar dilations (max: 26±3%). The level of protein O-GlcNAcylation was increased, whereas the P-eNOS (Ser-1177) was decreased in HG exposed vessels. These findings indicate that a high concentration of glucose may lead to glucosamine formation, which impairs histamine-induced, NO-mediated arteriolar dilations. We propose that interfering with the hexosamine pathway may prevent microvascular complications in diabetes.

Original languageEnglish (US)
Pages (from-to)115-121
Number of pages7
JournalVascular Pharmacology
Volume56
Issue number3-4
DOIs
StatePublished - Mar 1 2012
Externally publishedYes

Fingerprint

Hexosamines
Dilatation
Nitric Oxide
Histamine
Arterioles
Glucosamine
Proteins
Glucose
Azaserine
Video Microscopy
Nitric Oxide Donors
Nitric Oxide Synthase Type III
NG-Nitroarginine Methyl Ester
Nitroprusside
Diabetes Complications
Microvessels
Constriction
Nitric Oxide Synthase
Acetylcholine
Blood Vessels

Keywords

  • Diabetes mellitus
  • Glucosamine
  • Hexosamine pathway
  • Hyperglycemia
  • Microvessel
  • O-GlcNAcylation

ASJC Scopus subject areas

  • Pharmacology
  • Molecular Medicine
  • Physiology

Cite this

Activation of hexosamine pathway impairs nitric oxide (NO)-dependent arteriolar dilations by increased protein O-GlcNAcylation. / Beleznai, Timea; Bagi, Zsolt.

In: Vascular Pharmacology, Vol. 56, No. 3-4, 01.03.2012, p. 115-121.

Research output: Contribution to journalArticle

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abstract = "We hypothesized that under high glucose conditions, activation of the hexosamine pathway leads to impaired nitric oxide (NO)-dependent arteriolar dilation. Skeletal muscle arterioles (diameter: ~160μm) isolated from male Wistar rats were exposed to normal glucose (NG, 5.5mmol/L) or high glucose concentrations (HG, 30mmol/L, for 2h) and agonist-induced diameter changes were measured with videomicroscopy. Western blots were performed to identify the vascular levels of protein O-linked-N-acetyl-glucosamine (O-GlcNAc) and phosphorylated endothelial NO synthase (eNOS). In arterioles exposed to HG, dilations to histamine were abolished compared to those exposed to NG (max: -6±6{\%} and 69±9{\%}, respectively), while acetylcholine-induced responses were not affected. Inhibition of NO synthesis with N G-nitro-l-arginine methyl ester (L-NAME) reduced histamine-induced dilations in NG arterioles, but it had no effect on microvessels exposed to HG. Dilations to the NO donor, sodium nitroprusside and constrictions to norepinephrine and serotonin were similar in the two groups. In the presence of the inhibitor of hexosamine pathway, azaserine, histamine-induced dilations were significantly augmented in arterioles exposed to HG (max: 67±2{\%}). Moreover, exposure of vessels to glucosamine (5mmol/L, for 2h) resulted in reduced histamine-induced arteriolar dilations (max: 26±3{\%}). The level of protein O-GlcNAcylation was increased, whereas the P-eNOS (Ser-1177) was decreased in HG exposed vessels. These findings indicate that a high concentration of glucose may lead to glucosamine formation, which impairs histamine-induced, NO-mediated arteriolar dilations. We propose that interfering with the hexosamine pathway may prevent microvascular complications in diabetes.",
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