Evolution of renal oxygen content measured by BOLD MRI downstream a chronic renal artery stenosis.
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.
Rognant
Nicolas
N
Département de Néphrologie, Hôpital Edouard Herriot, F-69437 Lyon, France.
Guebre-Egziabher
Fitsum
F
Bacchetta
Justine
J
Janier
Marc
M
Hiba
Bassem
B
Langlois
Jean Baptiste
JB
Gadet
Rudy
R
Laville
Maurice
M
Juillard
Laurent
L
D000818:Animals; D002908:Chronic Disease; D004232:Diuretics / Q000008:administration & dosage; D005665:Furosemide / Q000008:administration & dosage; D000860:Hypoxia / Q000188:drug therapy / Q000209:etiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D051381:Rats; D017207:Rats, Sprague-Dawley; D012077:Renal Artery / Q000503:physiopathology*; D012078:Renal Artery Obstruction / Q000150:complications*
D004232:Diuretics; D005665:Furosemide; D010100:Oxygen