Surgical reduction of the renal mass in rats: morphologic and functional analysis on the remnant kidney

Abstract

ABSTRATCPurpose: This study has analyzed the giochemical and morphological effects on the remmant kidney in rats which were submitted to progressive surgical ablation of renal mass. Methods: Sixty Wistar male rats, weighing between 210 and 380g, were used and they were distributed in 3 groups of 20 animals each. The rats from the groups called 1, 2 and 3 were submitted to the surgical removal of renal tissue equivalent to ½, 2/3 and 5/6 of the whole renal mass, respectively. Then the groups were subdivided into 2 subgroups and they were operated again within 24 hours (subgroups 1B, 2B and 3B) and within 8 weeks (subgroups 1C, 2C and 3C) for the removal of the remnant kidney. 24-hour urine and blood were collected to analyze serum creatinine, clearance of creatinine and proteinuria in the first surgical intervention and at the time of the re-operation. The remnant kidney was submitted to a macroscopic evaluation for the degree of hypertrophy and to the analysis of histology. Results: There was a significant increase of the volume of the remnant kidney (164%) and glomerular sclerosis was present in 40% of the animals submitted to the ablation of 5/6 of renal mass. Functional alterations characterized by the increase of urinary excretion of proteins (50% in group 3), rise in the serum creatinine (261% subgroup 2B; 371% subgroup 3B, 118% subgroup 3C) and a significant reduction of the clearance of creatinine (control x subgroup 3C = 2,88 x 1,15 ml/min: p<0,05 were also observed. Conclusion: The compensatory renal hypertrophy, as well as the glomerular injury translated in the form of proteinuria and sclerosis, are closed related to the volume of the remnant kidney, thus they are more evident when a greater fraction of the renal tissue is excised. Key words: Kidney. Nephrectomy. Surgery. Creatinine. Rats. RESUMOObjetivo: O estudo analisou os efeitos bioquímicos e morfológicos sobre o rim remanescente em ratos submetidos à ablação cirúrgica progressiva da massa renal. Métodos: Foram utilizados 60 ratos machos Wistar, pesando entre 210 e 380g, distribuídos em 3 grupos contendo 20 animais cada. Os ratos dos grupos denominados de 1,2 e 3 foram submetidos à remoção cirúrgica de tecido renal equivalente a ½, 2/3 e 5/6 da massa renal total, respectivamente. Os grupos foram então subdivididos em 2 subgrupos e reoperados em 24 horas (subgrupos 1B, 2B, 3B) e em 8 semanas (subgrupos 1C, 2C, 3C) para remoção do rim remanescente. Foram obtidas coletas de urina de 24 horas e sangue para análise da creatinina sérica, depuração da creatinina e proteinúria na primeira intervenção cirúrgica e por ocasião da reoperação. O rim remanescente foi submetido à avaliação macroscópica do grau de hipertrofia e à análise histológica. Resultados: Houve aumento significativo do volume do rim remanescente (164%) e presença de esclerose glomerular em 40% dos animais submetidos à ablação de 5/6 da massa renal. Alterações funcionais caracterizadas pelo aumento da excreção urinária de proteínas (50% no grupo 3), elevação dos níveis séricos da creatinin...

Ultrastructural changes and nestin expression accompanying compensatory renal growth after unilateral nephrectomy in adult rats

“…3,4 The compensatory renal hypertrophy causes an increase in weight and/ or volume of the remaining kidney of the adult animals. [5][6][7][8] The nephrogenesis in rats and mice is accomplished during their neonatal period, while in humans, it occurs prenatally, and therefore, the renal growth that occurs does not include new nephron formation. 9,10 The nature of this compensatory growth was found to be rather hypertrophic than hyperplastic.…”

“…4,12,25,26 At the histopathologic level, kidney weight was used as the main most prominent indicator of the compensatory hypertrophy. 3,8 The compensatory growth can affect the glomeruli, proximal and distal convoluted tubules and also the cortical collecting ducts, 7,[27][28][29][30] with reports specifying that this growth occurs primarily in the cortex, especially confined to the proximal convoluted tubules. 11 The growth pattern resembles that of the natural growth of kidney during the postnatal period where hypertrophy of the proximal tubules is more than that of distal tubules.…”

Animal model of chronic kidney disease using a unilateral technique of renal ischemia and reperfusion in White New Zealand rabbits

“…Some studies conducted to establish an animal model of chronic kidney disease, used the two-surgical-times procedure, i.e., a first surgery is performed to establish the process of renal ischemia by clamping the unilateral renal pedicle and after a period that varied from four to 12 weeks, according to each protocol, a new surgical procedure is performed for the reduction of the renal mass to the contralateral organ that suffered the ischemic procedure [5][6][7] .…”

“…Moreover, the choice of animal model, the Wistar rats, due to their limited size and low blood volemia, impair blood samples for biochemical analyzes and the reduction of animal survival in the post-surgery [5][6][7] . Thus, in this experiment we chose to use the White New Zealand rabbits and one surgical time procedure, through the exclusive unilateral technique of renal ischemia and reperfusion.…”

“…There are some protocols in the literature for the development of an animal model of CKD in rats. A two time surgery in which the animal is first subjected to performing ischemia and reperfusion surgery, and after a period ranging from four to 12 weeks, the animal undergo a new surgical procedure to accomplish reduction of renal mass by nephrectomy at different rates 2/3, 4/5, 5/6 5,6 . This type of surgical technique results in a reduction of animal´s survival and in association with a low volemia of rats jeopardizes the use of this animal model on certain types of experiments, especially methodologic designs requiring long periods of observation.…”