Background: This study was designed to explore the application value of the Blood Oxygen Level–Dependent(BOLD) MRI and to detect if it was closely related to HIF-1α in renal hypoxia induced by unilateral ureteral obstruction(UUO).Methods: 40 healthy mice were included. UUO mice(n=32) drawn randomly were generated by complete ligation of the left ureteral. The remaining(n=8) were used as a sham-operated control. BOLD-f MRI was performed on pre-operation(day0). On days 1,3,5,7 after the operation, 8 mice drawn randomly from UUO were carried on MRI scan and were followed by histologic analysis on every time point. However,8 sham-operated mice were scaned on every time piont and executed on day 7.The renal cortex and medulla were calculated and measured on the workstation. Differences among the time points and between the slice of the kidney were assessed by using one-way analysis of variance. And R2* was correlated with HIF-1α expression at pearson correlation analysis.Results: In the diseased kidney, the R2* of renal cortex(28.51 ±3.47Hz), peripticon(35.89 ±1.88Hz) and opticon(28.80 ±5.15Hz) significantly increased over time(P < 0.05). And they were all closely positive correlated with increased HIF-1α expression(P < 0.001). In the contralateral kidney, the R2*of peripticon was decreased significantly in day5(P<0.05), and the R2*of cortex, peripticon and opticon were all decrease significantly in day7. Among renal layers,the R2*of peripticon was higher than cortex and opticon in normal kidneys(P<0.05).But the difference became smaller and smaller as the time after operation prolonged.Conclusion: In the study of UUO animal model, BOLD-f MRI technique can reflect the changes of renal paitial oxygen pressure. It may be potential to detect and evaluate renal hypoxia noninvasively in human. |