Experimental model for the study of chronic renal ischemia in rats. Morphologic, histological and ultra-structural analysis1 Modelo experimental para o estudo da isquemia renal crônica em ratos. Análises morfológica, histológica e ultra-estrutural

Purpose: To evaluate a model of chronic renal ischemia in rats and to characterize the effects on renal tissue. Methods: 168 Wistar rats were divided into two equal groups, control (GC) and ischemia (GI). The animals of the GI (n=84) were submitted to partial ligation of the left renal artery, and the animals of GC (n=84) stayed with the renal artery intact. In seven successive and identical periods of time, in weekly intervals, 12 animals of each group were submitted to nephrectomy, with morphometric determinations and histological and ultra-structural analysis. Results: The GI presented progressive reduction in renal weight, volume and cortical thickness observed from the 7th day of the experiment, reaching maximum degree in the 49th day (p < 0.05). The proximal tubular atrophy in the GI was observed in 75/84 analysis (89,2%), with highly significant difference among the groups starting from the 7th day (p=0 .0009) and in the other periods of the experiment (p=0 .00001). The most prevalent interstitial alteration was the infiltrate, present in 98,8% of the GI, with highly significant difference among the groups in the whole experiment (p=0 .00001). Ultra-structural analysis didn’t demonstrate glomerular lesions, evidencing that the glomerule preserves its intact architecture during chronic ischemia. Conclusion: The model showed that chronic renal ischemia in rats provokes progressive renal atrophy, with preservation of glomerular structure.