Evolution of renal oxygen content measured by BOLD MRI downstream a chronic renal artery stenosis

Nephrol Dial Transplant. 2011 Apr;26(4):1205-10. doi: 10.1093/ndt/gfq538. Epub 2010 Sep 3.

Abstract

Background: A decrease in renal oxygen content can be measured non-invasively by the increase of the R2* value derived from blood oxygen level-dependent magnetic resonance imaging (BOLD MRI). The aim of this study was to test if renal hypoxia occurs in kidneys downstream a chronic and unilateral renal artery stenosis.

Methods: Chronic renal ischaemia was induced in rats using a calibrated clip inserted on the right renal artery. R2* was determined, using a multiple recalled gradient-echo sequence, before and once a week after a clip insertion over 4 weeks, in a group of clipped (n = 8) and sham-operated (n = 7) rats.

Results: At baseline, in stenotic kidneys, R2* was higher in the outer stripe of outer medulla (105 ± 4.6) and the outer medulla (99 ± 2.5) than in the cortex (84 ± 2.5; P < 0.002 for comparison with both areas). R2* was unchanged in the cortex, the outer stripe of outer medulla and the outer medulla in stenotic kidneys, sham-operated kidneys and contralateral kidneys during the 4 weeks. Mean blood pressure was higher in rats with clipped kidney than in sham-operated rats from Day 11 and remained increased thereafter. The renal volume increased progressively in sham-operated kidneys and contralateral kidneys, whereas it slightly decreased in stenotic kidneys.

Conclusions: Our study shows that after 4 weeks, no renal hypoxia can be detected in the kidney downstream to a renal artery stenosis, suggesting that atrophy could be induced by other factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chronic Disease
  • Diuretics / administration & dosage
  • Furosemide / administration & dosage
  • Hypoxia / drug therapy
  • Hypoxia / etiology*
  • Magnetic Resonance Imaging*
  • Male
  • Oxygen / metabolism*
  • Oxygen Consumption
  • Rats
  • Rats, Sprague-Dawley
  • Renal Artery / physiopathology*
  • Renal Artery Obstruction / complications*

Substances

  • Diuretics
  • Furosemide
  • Oxygen