Experimental model for the study of chronic renal ischemia in rats: morphologic, histological and ultra-structural analysis

Abstract

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 7 th day of the experiment, reaching maximum degree in the 49 th 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 7 th 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. Key words: Kidney. Ischemia. Models, Animal. Rats. RESUMOObjetivo: Avaliar um modelo de isquemia renal crônica em ratos e caracterizar os efeitos no tecido renal. Métodos: Utilizaramse 168 ratos Wistar divididos em dois grupos iguais, controle (GC) e isquemia (GI). Os animais do GI (n=84) foram submetidos à ligadura parcial da artéria renal esquerda, e os animais do GC (n=84) permaneceram com a artéria renal intacta. Em sete períodos de tempo sucessivos e iguais, em intervalos semanais, 12 animais de cada grupo foram submetidos à nefrectomia, com determinações morfométricas e análises histológica e ultra-estrutural. Resultados: O GI apresentou redução progressiva no peso, volume e espessura cortical renal a partir do 7º dia do experimento, atingindo grau máximo no 49º dia (p < 0.05). A atrofia tubular proximal no GI ocorreu em 75/84 análises (89,2%), com diferença altamente significativa entre os dois grupos a partir do 7º dia (p=0.0009) e nos demais períodos do experimento (p=0.00001). A alteração intersticial mais comum no GI foi o infiltrado, presente em 98,8%, com diferença altamente significativa entre os dois grupos (p=0.00001). A análise ultra-estrutural não demonstrou lesões glomerulares, evidenciando que os glomérulos preservam sua arquitetura intacta durante a isquemia crônica. Conclusão: O modelo mostrou que a isquemia renal crônica em ratos provoca atrofia renal progressiva, com preservação da estrutura glomerular.

Collared Pecary (tayassu tajacu) as a new model of renal ischemic injury induced by clamping the renal artery

“…Partial or total glomerular sclerosis found in 100% of our animals is a common finding in rats and rabbits, as well as proximal tubular atrophy and increased apoptosis, common in experimentally induced CRF 1,35 .…”

“…In mice , morphological changes consistent with ischemic necrosis of renal tubular cells are found after at least 30 minutes of ischemia and after over an hour of reperfusion 49,50 and in rats subjected to ischemia only renal 1 . Common findings relate to renal injury in the ischemic swine model 51 .…”

“…Renal lesions were identified and classified according to adaptation of the methodology described by Konopka et al 1 .…”

“…Obstructive disease of the renal arteries or renovascular disease can produce two different and independent clinical conditions: renovascular hypertension and renal insufficiency (RI) 1 . Renovascular hypertension by clamping the artery was first described by Goldblatt et al 2 , pioneer in rat models, focused on pathophysiology study and renovascular hypertension treatment.…”

“…The renal ischemia induction model has previously been performed in animals such as rats 1 and pigs 5 to analyze the severity and extent of injury and to evaluate therapeutic treatments for secondary hypertension 6 .…”