Mannitol reduces nephron loss after warm renal ischemia in a porcine model.

BACKGROUND: Mannitol has been employed to ameliorate renal warm ischemia damage during partial nephrectomy, however, there is limited scientific evidence to support the use of mannitol during partial nephrectomy. The objective of the present study was to investigate the glomerular number after renal warm ischemia, with and without the use of mannitol in a Pig Model. METHODS: Twenty-four male pigs were assigned into three groups. Eight animals were allocated to the sham group that was subjected to laparoscopic dissection of the left renal hilum, without renal ischemia. Eight animals were allocated to the ischemia group that had the left renal hilum clamped for 30 min through laparoscopic access. Eight animals received mannitol (250 mg/kg) before the occlusion of renal hilum for 30 min. The kidneys were collected after the euthanasia of the pigs 21 days post surgery. The right kidney was utilized as a self-control for each animal. Serum creatinine, urea levels, the weight and volume of the kidneys were measured. Glomerular volumetric density, volume-weighted glomerular volume, and cortical volume were quantified through stereological methods and employed to determine the number of nephrons per kidney. Student's t test and ANOVA were used for statistical analysis. RESULTS: In the ischemia group, the left kidney recorded a reduction of 24.6% (290, 000 glomeruli) in the number of glomeruli in comparison to the right kidney. Kidneys subjected to ischemia also displayed decreased weight and volume in comparison to the sham and mannitol groups. No difference was observed between the left and right kidneys from the sham and mannitol groups. Further, no distinction in serum creatinine and urea among the groups was observed. CONCLUSION: The use of mannitol significantly reduces nephron loss during warm ischemia in pigs.

Glomerular Morphology and Renal Function after Warm Ischemia by Main Artery or Selective Clamping in a Porcine Model.

OBJECTIVE: The study aimed to evaluate the ischemic and non-ischemic areas after selective arterial occlusion by using stereological analysis of glomeruli, and to compare them with main arterial clamping and sham-operated animals. MATERIALS AND METHODS: Twenty-four male pigs were used in the study. The animals were divided into 3 groups with 8 animals in each as follows: group sham, submitted to laparoscopic dissection of the renal pedicle but not submitted to ischemia; group arterial (A), submitted to left renal artery clamping; and group selective (S), submitted to left renal artery caudal branch occlusion. Groups A and S underwent 30 min of warm ischemia. Left and right kidneys were collected after 21 days and renal fragments were processed for stereological evaluation. Glomerular volume density (Vv[glom]), mean glomerular volume (MGV), and glomerular density were measured. Serum creatinine and urea were assessed preoperatively, 10 days after surgery, and before euthanasia. RESULTS: There was no significant difference among groups with regard to renal function. Renal weight and volume were similar among groups. Also, no difference was observed between the groups with regard to Vv[glom], MGV, and glomerular density, both when compared to its right control or when left kidneys were compared. CONCLUSIONS: Selective arterial clamping technique was neither superior nor inferior to main artery clamping.

The sheep as a model for healing studies after partial nephrectomy.

BACKGROUND: The pig has been considered the best model for renal surgery. However, recent research has demonstrated that the kidney of pigs heals differently from that of humans. The objective of this study was to evaluate sheep as an alternative animal model for studying collecting system healing after laparoscopic partial nephrectomy. MATERIALS AND METHODS: The caudal pole of the left kidney was removed from eight female adult domestic sheep using laparoscopic partial nephrectomy. Monopolar energy was used for hemostasis only in the parenchyma, avoiding coagulation near the collecting system, which was left opened. After 14 d, all animals were euthanized, and their left kidney was removed. Serum levels of urea and creatinine were assessed preoperatively and postoperatively (on days 2, 6, 10, and 14), and peritoneal fluid samples were collected during necropsy for urea and creatinine evaluation. An ex vivo retrograde pyelogram was performed, and a retrograde injection of methylene blue ink was administered to evaluate urinary leakage. Samples from the operated pole were analyzed using histologic methods. RESULTS: During necropsy, an urinoma surrounding the operated kidney was observed in one animal. Peritoneal fluid levels of urea and creatinine were elevated. Retrograde pyelograms exhibited contrast-medium extravasation through the operated pole in all kidneys. The opened collecting system was also confirmed by methylene blue ink injection. The operated pole was covered by collagenous tissue and adhered to adjacent organs. CONCLUSIONS: Sheep should be considered as an adequate experimental model for research on collecting system healing after partial nephrectomy.