PARTIAL UNILATERAL URETERAL OBSTRUCTION IN
NEWBORN RAT
Wen
Jianguo, 3rd Teaching Hospital of Zhengzhou University, China
Objective: We investigated the feasibility of
creating a mild and a severe PUUO in newborn rats, the long-term effects of
neonatal PUUO on renal hemodynamics and morphology, and the dynamic changes
in renal relative signal intensity (RSI) using magnetic resonance imaging
(MRI).
Methods: Two degrees of PUUO were
created by embedding the upper fourth or the upper two-thirds of the left
ureter into the psoas muscle, which was characterized by pelvic pressure
measurement in 50 young rats. The long-term effects of neonatal PUUO on
renal hemodynamics and morphology were investigated in 56 rats. The dynamic changes in RSI using MRI enhanced by Gd-DTPA in 35 rats
were investigated in 1-year-old rats with partial, complete unilateral
ureteral obstruction and sham-operated controls.
Results: A mild or a severe
obstruction can be created by embedding different lengths of ureter into
the psoas muscle. Both mild and severe obstruction caused a time-dependent
decrease in renal blood flow. At week 24, the mean renal blood flow (RBF)
had decreased to 79% and 57% of controls in the mildly and severely
obstructed kidneys, respectively (p < 0.05). The renal pelvis volume
increased and the renal parenchymal volume decreased significantly in the
severely obstructed compared to the mildly obstructed kidneys. A significant increase in renal volume of contralateral
non-obstructed kidneys did not develop immediately after the onset of
functional deterioration in partially obstructed kidneys. A repeatable RSI
pattern including 3 phases after Gd-DTPA
administration was
observed in normal kidneys. In PUUO, the 3 phases
were significantly slower than that in controls.
Conclusion: Different degree of PUUO can be created by embedding different
lengths of ureter into psoas muscle, and RBF can be investigate by using
MRI. The Gd-DTPA enhanced dynamic MRI provides not only useful information
for distinguishing obstructed from non-obstructed but also the changes in
renal concentration ability.