FUNCTIONAL AND ANATOMICAL CHANGES IN THE KIDNEY FOLLOWING EXPERIMENTAL PARTIAL URETERAL OBSTRUCTION

Abstract

An experimental model of chronic hydronephrosis due to an extrinsic partial ureteral obstruction was produced in Wistar rats. The reproducibility and quality of this experimental hydonephrosis were determined by intravenous pyelography, renal cortical blood flow studies using a hydrogen gas clearance method, histological and microangiographic studies. The partial obstruction was induced by instilling a droplet of an α-cyanoacrylate monomer solution around the left lower ureter. Hydronephrosis produced by a complete double ligation of the ureter was used as control. On the basis of IVP findings, the degree of hydronephrosis was rated on the following basis: normal=grade 0, moderate=grade I, severe=grade II and no opacification=grade III. Out of 105 rats, a moderate or severe progressive hydronephrosis occurred in 97 one week after the induction of hydronephrosis; grades 0, I, II and III were observed in 6 (5.7%), 75 (71.4%), 22 (21%) and 2 rats (1.9%), respectively. In these kidneys, renal cortical hemodynamics decreased gradually in course of time, and the decreasing rate was less progressive than that in the complete ligation group. The microangiograph demonstrated an appreciable amounts of well-preserved glomeruli even at the terminal stage of the experiment and a gradual decreasing rate of the distribution of the glomeruli. In addition, the histological study revealed that hydronephrotic changes in this model were milder and less progressive than those in the complete ligation group.
In conclusion, the present model has a high reproducibility in developing chronic hydronephrosis and may be introduced to the experimental studies of pyelonephritis, renal function, renal stone formation and others.