Objective To investigate the influence of different warm ischemia time on renal function after renal ischemia-reperfusion injuiy in mice and its correlation with kidney injuiy molecule-1(KIM-1),so as to assisting urologists lo optimize the time of renal arteiy occlusion during the surgery of partial nephrectomy.Methods A total of 36 male C57BIV6 mice were divided randomly into 4 groups(Sham,28 Min,30 Min and 32 Min)according to different renal pedicle occlusion duration.Serum creatinine(S cr)and blood urea nitrogen(BUN)were monitored before surgery,and at each time-point of 24 hours,72 hours and weekly from 1 week to 6 weeks after the surgeiy.Western blot and ininiunonuoreseence staining were used to detect the KIM-1 expression in kidney proximal tubular cells(PTCs)in the acute phase of 48 hours post the procedure.Picrosirius red staining was used to evaluate the kidney fibrosis severity as the indii-ator of chronic phase of kidney injury 6 weeks post the surgery.Results A half of mice in the group of 32 Min died within 1 week after the surgeiy,while mice in the other groups survived until euthanasia.Phe mice receiving renal pedicle occlusion exhibited incTeased Scr and BUN after the surgen while the sham-operated mice did not.The peak concentration of Scr and BUN both appeared at 24 hours post the surgen-,then decreased gradually till 2 weeks after the surgery and sustained stably thereafter.The peak and steady concentration of Scr and BUN showed a positive correlation with warm ischemia duration.Western blot and immunofluorescence staining showed FrCs presenting KIM-1 promptly and dramatically increased 48 hours post the surgeiy and indicated a positive correlation between KIM-1 expression and the warm ischemia duration.Moreover,picrosirius red staining implicated that the kidney librosis also deteriorated with the extended warm ischemia time.Conclusions The severity of kidney injuiy deteriorates with the extended warm ischemia time.Hie mice surviving the episode of acute kidney injury(AKI)could make a full renal recove r'when the injury in the acute phase is mild.However,AKI is appreciated to he markedly associated with increased risk of future chronic kidney disease and end-stage renal disease wiien the injury is severe.KIM-1 could be used as a biomarker to indicate the ischemia-repe^rfusion injury inducing kidney injury and to evaluate the severity.