Modulation of extracellular superoxide dismutase expression by angiotensin II and hypertension

Tohru Fukai, Martin R. Siegfried, Masuko Fukai, Kathy K. Griendling, David G. Harrison

Research output: Contribution to journalArticle

159 Scopus citations

Abstract

Angiotensin II and hypertension increase vascular oxidant stress. We examined how these might affect expression of the extracellular superoxide dismutase (ecSOD), a major form of vascular SOD. In mice, angiotensin II infusion (1.1 mg/kg for 7 days) increased systolic blood pressure from 107±3 to 152±9 mm Hg and caused a 3-fold increase in ecSOD, but there was no change in the cytosolic Cu/Zn SOD protein, as determined by Western blot analysis. This was associated with a similar increase in ecSOD mRNA as assessed by RNase protection assay and was prevented by losartan. Induction of ecSOD by angiotensin II was not due to hypertension alone, because hypertension caused by norepinephrine (5.6 mg · kg-1 · d-1) had no effect on ecSOD. Similarly, exposure of mouse aortas to angiotensin II (100 nmol/L) in organoid culture increased ecSOD by ~2-fold. In the organoid culture, angiotensin II-induced upregulation of ecSOD was prevented by losartan (10 μmol/L) and PD985059 (30 μmol/L), a specific inhibitor of p42/44 MAP kinase kinase. Angiotensin II activates the NADH/NADPH oxidase; however, diphenyleneiodonium chloride (10 μmol/L), an inhibitor of this oxidase, did not prevent p42/44 MAP kinase phosphorylation or ecSOD induction by angiotensin II. Finally, in human aortic smooth muscle cells, angiotensin II moderately increased transcriptional rate (as assessed by nuclear run-on analysis) but markedly increased ecSOD mRNA stability. Thus, angiotensin II increases ecSOD expression independent of hypertension, and this increase involves both an increase in ecSOD transcription and stabilization of ecSOD mRNA. This effect of angiotensin II on ecSOD expression may modulate the oxidative state of the vessel wall in pathological processes in which the renin-angiotensin system is activated.

Original languageEnglish (US)
Pages (from-to)23-28
Number of pages6
JournalCirculation Research
Volume85
Issue number1
DOIs
StatePublished - Jul 9 1999
Externally publishedYes

Keywords

  • Angiotensin II
  • Hypertension
  • Norepinephrine
  • Superoxide
  • Superoxide dismutase

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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