Effect of free radical scavenger (tempol) on intrarenal oxygenation in hypertensive rats as evaluated by BOLD MRI

Purpose: To demonstrate a differential response following administration of a free radical scavenger, tempol, in kidneys of hypertensive compared to normotensive rats. Material and Methods: Data were obtained in spontaneously hypertensive rats (SHR, N = 5). Wistar-Kyoto rats (WKY, N = 6) were used as normotensive controls. Results: Consistent with prior reports, SHRs show a significant response to tempol (R(2)(*)decreased from 40.56 +/- 0.66 second(-1) to 28.58 +/- 0.6 second(-1) in medulla, P < 0.05), while WKY rats exhibit a minimal change (R-2(*) measuring 22.36 +/- 4.38 second(-1) pre-tempol and 21.57 +/- 4.78 second(-1) post-tempol, in medulla). The post-tempol R-2(*) in SHR was found to be comparable to pre-tempol values in WKY rats, suggesting an improved medullary oxygenation in SHRs. Conclusion: Based on both baseline R2* values and the differential effect of the free radical scavenger on renal medullary oxygenation, BOLD MRI can distinguish hypertensive from normal kidney in rats.