2.3. Serum and Urinary Biomarker Quantification

We collected about 0.3 mL blood from the tail vein prior to the development of AKI and obtained 1 mL blood after puncturing the abdominal aorta during sacrifice 24 h after CM injection. We collected serum after clotting at 4°C overnight and centrifugation at 2000g for 15 min. SCr concentrations were tested using the QuantiChrom™ Creatinine Assay Kit and Urea Assay Kit (BioAssay Systems, Hayward, CA, USA). We used bladder puncture to collect urine 30 min after anesthesia 24 h after CM injection. We determined urinary and serum NGAL concentrations utilizing a rat NGAL enzyme-linked immunosorbent assay (ELISA) kit from Abcam (Cambridge, MA, USA).