Objective  To explore a novel method for establishing rabbit models with renal ischemia-reperfusion injury (IRI) under hypothermic, normothermic and hyperthermic environments and evaluate the effect of the reperfusion under hypothermic environment on renal IRI in rabbits.

  Methods  Sixty healthy New Zealand rabbits were randomly and evenly divided into five groups:control group (A group, n=12), sham operation group (B group, n=12), hypothermic reperfusion group (C group, n=12), normothermic reperfusion group (D group, n=12) and hyperthermic reperfusion group (E group, n=12).The serum creatinine (Scr) and blood urea nitrogen (BUN) levels were measured daily within postoperative 7 d.The content of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) in the renal tissues were measured at postoperative 1 d.Hematoxylin-eosin (HE) staining was performed to observe the histopathological changes at postoperative 1 d.Terminal deoxynucleotidyl transferase (TdT)-dUTP nick-end labeling (TUNEL staining) was adopted to detect the cellular apoptosis at postoperative 1 d.

  Results  At 1 d after operation, the Scr and BUN levels in C, D and E groups were significantly higher than those in A and B groups (all P < 0.01).Compared with C group, the Scr and BUN levels were more notably increased in D and E groups (both P < 0.05).Within 7 d after surgery, the Scr and BUN levels tended to decline in C, D and E groups.Compared with D and E groups, the Scr and BUN levels were significantly lower in C group (both P < 0.05).Compared with A and B groups, the MDA contents were considerably increased, whereas the SOD activities were significantly decreased in C, D and E groups (all P < 0.01).Compared with C group, the MDA content was more significantly enhanced, whereas the SOD activity was remarkably decreased in D and E groups (both P < 0.01).At postoperative 1 d, the pathological examination of the renal tissues demonstrated that the renal morphology was normal in A and B groups, whereas significant renal damage was observed in D and E groups.Compared with D and E groups, the severity of renal injury was less in C group.TUNEL staining revealed that the quantity of positive renal tubular epithelial cells was significantly increased in D and E groups, and positive cells were also seen in the lumen.The quantity of positive cells in C group was significantly lower than those in D and E groups.

  Conclusions  The reperfusion rabbit models under different temperature environments can be established by covering the kidney by ice soil and persistent administration of 37 ℃ and 40 ℃ saline.Hypothermic reperfusion exerts a protective effect on renal IRI.