Change of Collagen after Partial Ureteral Obstruction in Rat Kidney

Lee, Kyoung Jun; Lee, Chung Bum; Yoon, Jai Young; Cho, Dae Haeng; Hwang, Tae Kon

Abstract

PURPOSE: Chronic ureteral obstruction results in changes in renal hemodynamics, tubular function, and subsequently fibrosis of the tubulointerstitium. The pathologic marker of irreversible renal injury is interstitial fibrosis. The degree of interstitial fibrosis is the most useful measure of the degree of renal injury. This study in rats with partial ureteral obstruction was performed to describe and quantify the changes in collagen deposition.
MATERIALS AND METHODS
Female Sprague-Dawley rats weighing 300-400g were used. Individual kidneys were obtained from rats at 1, 2, 3, 4 weeks after partial ureteral obstruction and sham operation. The total amount of collagen was measured from its contents of hydroxyproline by assuming that hydroxyproline is 14% in weight of the collagen. Collagen types I, III, and IV were localized by immunohistochemical staining and the distribution of each collagen type was analized using differences of their staining densities.
RESULTS
After 2 weeks of partial ureteral obstruction, the total amount of collagen in affected kidney was significantly increased compared to control and 1 week groups(P<0.05). All of the collagen types in the interstitium of the affected kidney was gradually increased parallel to the duration of partial ureteral obstruction. Collagen type IV was increased significantly in tubular basement membrane and interstitium after 2 weeks of partial obstruction compared to control and 1 week groups.
CONCLUSIONS
The partial ureteral obstruction causes progressive increase of amount of collagen according to the duration of obstruction, especially after 2 weeks, and tubulointerstitial fibrosis of obstructive nephropathy is closely related to collagen type I, III, and IV. Infiltration of collagen type IV in tubular basement membrane may play a major role in obstructive nephropathy.