Blood urea nitrogen

Serum was collected at 48 h of reperfusion at the time of animal sacrifice. Commercially available kits were utilized to measure urea (blood urea nitrogen, BioAssay Systems, Hayward, CA, USA) and creatinine levels (Pointe Scientific, Canton, MI, USA) according to the manufacturer’s instructions. Histology was examined in both the uninjured kidney excised at the time of IRI surgery and the injured kidney excised at the time of sacrifice. The tissue was fixed in 10% neutral buffered formalin and embedded in paraffin, sectioned, and stained with a standard periodic acid-Schiff (PAS) protocol. To score tissue injury, high power microscopic images comprising the entire cortex and corticomedullary region of a single tissue section for each mouse were obtained. The images were scored by an investigator blinded to group assignment according to the following scale: 0 = no injury; 1 = 1 to 25% of parenchyma affected by injury; 2 = 26–50% involvement; 3 = 51–75% involvement; and 4 = 76–100% involvement. Injury was defined as dilated tubules, casts, cell sloughing, or loss of brush borders. Scores for the images from each mouse were averaged to obtain a single score for that animal, and then a group average was calculated.