Regulation of the vascular extracellular superoxide dismutase by nitric oxide and exercise training

J Clin Invest. 2000 Jun;105(11):1631-9. doi: 10.1172/JCI9551.


The bioactivity of endothelium-derived nitric oxide (NO) reflects its rates of production and of inactivation by superoxide (O(2)(*-)), a reactive species dismutated by extracellular superoxide dismutase (ecSOD). We have now examined the complementary hypothesis, namely that NO modulates ecSOD expression. The NO donor DETA-NO increased ecSOD expression in a time- and dose-dependent manner in human aortic smooth muscle cells. This effect was prevented by the guanylate cyclase inhibitor ODQ and by the protein kinase G (PKG) inhibitor Rp-8-CPT-cGMP. Expression of ecSOD was also increased by 8-bromo-cGMP, but not by 8-bromo-cAMP. Interestingly, the effect of NO on ecSOD expression was prevented by inhibition of the MAP kinase p38 but not of the MAP kinase kinase p42/44, suggesting that NO modulates ecSOD expression via cGMP/PKG and p38MAP kinase-dependent pathways, but not through p42/44MAP kinase. In aortas from mice lacking the endothelial nitric oxide synthase (eNOS), ecSOD was reduced more than twofold compared to controls. Treadmill exercise training increased eNOS and ecSOD expression in wild-type mice but had no effect on ecSOD expression in mice lacking eNOS, suggesting that this effect of exercise is meditated by endothelium-derived NO. Upregulation of ecSOD expression by NO may represent an important feed-forward mechanism whereby endothelial NO stimulates ecSOD expression in adjacent smooth muscle cells, thus preventing O(2)(*-)-mediated degradation of NO as it traverses between the two cell types.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Aorta / enzymology
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Muscle, Smooth, Vascular / enzymology*
  • Nitric Oxide / physiology*
  • Nitric Oxide Synthase / physiology
  • Nitric Oxide Synthase Type II
  • Nitric Oxide Synthase Type III
  • Physical Conditioning, Animal*
  • RNA, Messenger / analysis
  • Superoxide Dismutase / biosynthesis*
  • Superoxide Dismutase / genetics
  • Superoxides / metabolism


  • RNA, Messenger
  • Superoxides
  • Nitric Oxide
  • NOS3 protein, human
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type II
  • Nitric Oxide Synthase Type III
  • Nos3 protein, mouse
  • Superoxide Dismutase