BOLD MRI may be useful for demonstrating the change in R2 in CP-induced nephrotoxicity in rats. The changes in the CP+HW group were suspected to be due to a reduction of cytotoxic oxygen radicals.
Purpose: We assessed intrarenal oxygenation in gentamicin-induced nephrotoxicity (GIN) and the protective eŠect of hydrogen-rich water (HW) against GIN using blood oxygenation level-dependent magnetic resonance (MR) imaging.Materials and Methods: We acquired T 2 * -weighted images (T 2 * WI) of 21 rats on Days 0, 2, 4, and 7 using a 1.5-tesla MR imaging system. The rats were divided into 3 groups of seven each: control rats had free access to standard water and no gentamicin (GM) injection; rats designated the GM group had free access to standard water and were injected with GM (80 mg/kg/day) subcutaneously for 7 days; and the third group, designated the GM+HW group, had free access to HW and were injected with GM. R 2 * (=1/T 2 *) was estimated from T 2 *WI.Results: R 2 * values in the cortex were signiˆcantly decreased on Days 2, 4, and 7 compared with those on Day 0 in the GM group but not signiˆcantly changed in the control and GM+HW groups. R 2 * values in the medulla did not change signiˆcantly in any group.Conclusions: Ourˆndings suggested reduced oxygen utility, mainly in the cortex, in gentamicin-induced nephrotoxicity and an ameliorative eŠect of hydrogen-rich water against GIN.
The authors developed a method to quantitatively evaluate renal function using dynamic contrast-enhanced computed tomography (DCE-CT) and a compartment model. They applied this method to evaluation of drug-induced nephrotoxicity in rats. They performed the DCE-CT studies using a total of 36 male Sprague-Dawley rats (n=9 for control and n=27 for treatment). The rats in the drug-treated groups were given 1.8 mg/kg/day of cis-dichlorodiammineplatinum (cisplatin) intraperitoneally every other day twice (n=9), four times (n=9), or six times (n=9). The rate constants for the transfer of the contrast agent (CA) from the intravascular space to the renal corpuscle and tubular space via glomerular filtration (K1), outflow of the CA from the renal tubules (k2), and the fraction of blood volume (f) were estimated from the DCE-CT data, and their functional images were generated using the linear least squares method. When estimating the above parameters, the partial volume effect (PVE) on the arterial input function was corrected using a calibration curve obtained by phantom experiments. The endogenous creatinine clearance (Ccr) was also measured for comparison. The K1 images became lower and more heterogeneous and the K1 values decreased significantly with increasing cisplatin injection number (3.20+/-0.73, 2.49+/-0.75, 1.80+/-0.36, and 1.27+/-0.47 ml/ml/min for control, two-, four-, and six-times treated groups, respectively). When the PVE was not corrected, the K1 values were overestimated by 15+/-3% as compared with the case when the PVE was corrected. There was a good correlation between K1 and Ccr (r=0.903 and 0.901 for cases with and without correction of PVE, respectively). In conclusion, the authors' method using DCE-CT appears to be useful for quantitatively evaluating the extent of renal dysfunction such as renal damage due to drug-induced nephrotoxicity.
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