Hypoxanthine as a graft ischemia marker stimulates catalase activity in the renal vein during reperfusion in humans

BACKGROUND: The impairment of organ function derived from ischemia-reperfusion injury is still an important problem in solid organ transplantation. Cell alterations induced by ischemia prime the tissue for subsequent damage occurring during the reperfusion phase. Purine nucleotides and oxypurines are products of adenine nucleotide degradation. Reperfusion and reoxygenation are characterized by great production of reactive oxygen species and free radicals. On the contrary, superoxide dismutase, catalase, glutathione, and glutathione peroxidase are involved in protecting against free radicals. The aim of the study was to examine the correlation between concentrations of ischemia markers (hypoxanthine or inosine) and the activity of erythrocyte superoxide dismutase, catalase, or glutathione peroxidase. PATIENTS AND METHODS: The study included 40 renal transplant recipients. Before anastomosis of the kidney vessels with the recipient's iliac vessels, a "0" blood sample was taken from the iliac vein. Then, after anastomosis, the renal vein of the graft was cannulated and blood samples I, II, and III were obtained. The reperfusion of the transplanted kidney was measured with a thermovision camera ThermaCAM SC500. RESULTS: The plasma concentrations of hypoxanthine and inosine increased in statistically significant fashion immediately after total tissue reperfusion (P < .0001). Catalase activity at 4 minutes after total tissue reperfusion correlated positively with hypoxanthine concentrations immediately after total tissue reperfusion (Rs = +0.49), 2 minutes after total tissue reperfusion (Rs = +0.47), and 4 minutes after total tissue reperfusion (Rs = +0.46). There were no statistically significant correlations between hypoxanthine or inosine concentrations or superoxide dismutase or glutathione peroxidase activities. CONCLUSIONS: The results of the present study suggest that catalase activity may correlate with the concentration of hypoxanthine in the graft renal vein and other mediators of oxidative stress.