Oxygen concentration regulates NO-dependent relaxation of aortic smooth muscles

Yoshiki Takehara, Hiroko Nakahara, Shohei Okada, Kiyonori Yamaoka, Keisuke Hamazaki, Akihiro Yamazato, Masayasu Inoue, Kozo Utsumi

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Nitric oxide (NO) functions as an endothelium-derived relaxation factor and regulates vascular resistance. Recent studies in this laboratory revealed that the lifetime of NO significantly increased at physiologically low levels of oxygen concentrations and, hence, this gaseous radical strongly inhibited mitochondrial electron transport for a fairly long duration at low oxygen concentrations. The present work describes the effect of oxygen concentration on NO-induced relaxation and guanylate cyclase (GC) activity of endothelium-denuded aorta of the rat. Both NO and 2,2'-(hydroxynitrosohydrazono)bis-ethanamine (NOC18), an NO donor, induced the relaxa-tion of endothelium-denuded helical segments of rat aorta which were contracted by norepinephrine. NO-dependent relaxation of arterial specimens was enhanced by lowering oxygen concentration in the medium with concomitant increase in their cGMP levels. Anoxia induced the relaxation of the aorta by some NO-enhanceable and methylene blue-insensitive mechanism. These results suggested that local concentrations of oxygen might play important roles in the regulation of NO-dependent GC activity and vascular tonus of resistance arteries.

Original languageEnglish
Pages (from-to)287-294
Number of pages8
JournalFree Radical Research
Issue number4
Publication statusPublished - 1999
Externally publishedYes


  • Aorta
  • Guanylate cyclase
  • Hypoxia
  • Nitric oxide
  • Smooth muscle
  • cGMP

ASJC Scopus subject areas

  • Biochemistry


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