[Pathological study on the effect of oral adsorbent AST-120 on chronic renal failure in rats].

In order to evaluate the direct or indirect effect of AST-120 on chronic renal failure (CRF) in rats, histological and electron microscopical examinations were performed. A total of 30 Sprague-Dawley rats (aged 11 weeks and weighing 226 to 229 gm) with CRF induced by 5/6 nephrectomy were prepared. Rats were fed by a commercial diet (CE-2, Japan Kurea) and were divided into two groups: A (16 rats) and B (14 rats). AST-120 (5% content) was only administered to group B. After two months, kidneys were removed and prepared for the histological and electron microscopical examinations. On histological examination, group A kidneys showed severe glomerular hyalinization (more than 80%) and frequent crescents, as well as tubulo-interstitial fibrosis and many protein casts. In contrast, segmental glomerular lesions were identified in group B kidneys. Tubulo-interstitium were also well preserved. Furthermore, the ultrastructural findings of group B were milder than that of group A. The preservation of renal tissue in group B revealed the beneficial effect of AST-120 on CRF rats' kidneys. In conclusion, this beneficial effect is provided by the removal of the serum toxic metabolite (uremic toxin) and the precursor substance of the toxin by orally administered AST-120.