Experimental diffuse interstitial renal fibrosis. A biochemical approach.

In this paper we describe two simple experimental models of diffuse interstitial renal fibrosis in the rat. One develops 25 days after unilateral renal vein ligation, and the other 15 days after unilateral ureteral double ligation and section. In both models fibrosis is examined morphologically and biochemically, the latter with emphasis on collagen turnover. In addition to a description of the histology, also presented are quantitative biochemical data on four features of tissue collagen turnover, namely total content, concentration, biosynthesis, and degradation. Although the microscopic picture of both models can be adequately described as interstitial diffuse renal fibrosis, their mechanisms are different: unilateral renal vein ligation is an example of collapse fibrosis, whereas unilateral ureteral double ligation and section is a model of absolute fibrosis. In both models however, decreased collagen degradation is the significant metabolic abnormality.