Reduced oxygenation in diabetic rat kidneys measured by T2* weighted magnetic resonance micro-imaging.
By applying invasive techniques for direct measurements of oxygen tension, we have reported decreased kidney oxygenation in experimental diabetes in rats. However, the non-invasive MRI technique utilizing the BOLD effect provides several advantages with the possibility to perform repetitive measurements in the same animals and in human subjects. In this study, we applied a modified single gradient echo micro-imaging sequence to detect the BOLD effect in kidneys of diabetic rats and compared the results to normoglycemic controls. All measurements were performed on inactin-anaesthetized adult male Wistar Furth rats. Diabetes was induced by streptozotocin (45 mg/kg) 14 days prior to MRI-analysis. Sixteen T2*-weighted image records (B0=1.5 T) were performed using radiofrequency spoiled gradient echo sequence with 2.6 ms step increments of TE (TE1=12 ms), while TR (75 ms) and bandwidth per pixel (71.4 Hz) were kept constant. T2* maps were computed by mono-exponential fitting of the pixel intensities. Relaxation rates R2* (1/T2*) in cortex and outer stripe of the outer medulla were similar in both groups (cortex for controls 22.3 +/- 0.4 vs. diabetics 23.1 +/- 1.8 Hz and outer stripe of outer medulla for controls 24.9 +/- 0.4 vs. diabetics 26.4 +/- 1.8 Hz; n=4 in both groups), whereas R2* was increased in the inner stripe of the outer medulla in diabetic rats (diabetics 26.1 +/- 2.4 vs. controls 18.8 +/- 1.4 Hz; n=4, P<0.05). This study demonstrates that experimental diabetes in rats induces decreased oxygenation of the renal outer medulla. Furthermore, the proposed T2*-weighted MR micro-imaging technique is suitable for detection of regional changes in kidney oxygenation in experimental animal models.
Edlund
Jenny
J
Department of Medical Cell Biology, BMC, PO Box 571, Uppsala University, 751 23 Uppsala, Sweden.
Hansell
Peter
P
Fasching
Angelica
A
Liss
Per
P
Weis
Jan
J
Glickson
Jerry D
JD
Palm
Fredrik
F
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D007668:Kidney / Q000033:anatomy & histology / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D008297:Male; D009929:Organ Size; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013311:Streptozocin / Q000494:pharmacology
D013311:Streptozocin; D010100:Oxygen