Acute Kidney Injuries Induced by Various Irrigation Pressures in Rat Models of Mild and Severe Hydronephrosis

Objective To clarify whether tolerance to irrigation pressure could be modified over varying degrees of kidney obstruction during the endoscopic treatment of kidney stones in a rat model. Methods A total of 126 rats were randomly allocated into 2 experimental groups and a control group. The experimental groups underwent a surgical procedure to induce mild (group M, n = 60) or severe (group S, n = 60) hydronephrosis. In each group, the rats were then randomly allocated into 4 subgroups (M0 to M3 and S0 to S3) of respectively 6, 18, 18, and 18 rats. Groups 0 to 3 were respectively perfused with 0 (no irrigation), 20, 60, and 100 mm Hg pressure fluid. The control group underwent no surgical procedures and was only perfused with 100 mm Hg pressure fluid. Acute kidney injuries were assessed by analyzing the kidney microstructure, tubular cell apoptosis, kidney injury molecule-1, and cysteine-rich 61 (Cyr61/CCN1) expression using immunohistochemistry. Results No abnormalities were observed for the control group, groups 0, or 1. In group 2, abnormalities were observed only in the S group, whereas all kidneys in group 3 suffered acute kidneys injuries, along with occurrence of tubular cells necrosis, increased apoptosis, and increased expression of kidney injury molecule-1 and Cyr61. Conclusion Rats with severely obstructed kidneys were more likely to suffer acute kidney injuries than those with less obstructed kidneys when exposed to higher kidney irrigation pressures. This suggests that the pressure should be controlled and reduced when performing endourologic procedures in the context of kidney obstruction.