This is a randomized, single-blind, prospective, controlled clinical trial. The patients will be randomly assigned to the control group or dexmedetomidine group. After induction of anesthesia, the patients in the control group will receive regular perioperative care. The patients in the dexmedetomidine group will receive perioperative dexmedetomidine continuous intravenous infusion after induction of anesthesia till 2 hours after the end of the operation. All patients will receive sublingual microcirculation examination, laser speckle contrast imaging measurement of transplanted kidney surface microvascular blood flow intensity, laboratory tests of blood urine nitrogen, creatinine, and enzyme-linked immunosorbent assays of serum level of endocan, diamine oxidase, and neutrophil gelatinase-associated lipocalin at preset time points. The urine level of neutrophil gelatinase-associated lipocalin will also be measured. The vital signs and urine output will be recorded. The difference between the two groups will be compared.