Impact of different combined preservation modalities on warm ischemic kidneys: effect on oxidative stress, hydrostatic perfusion characteristics and tissue damage.

Hemodynamic disorders in brain dead organ donors induce hypoxia, warm ischemia and finally tissue damage. A cold preservation period also induces tissue and cellular lesions. The two major modes of preservation are cold storage (CS) and hypothermic pulsatile perfusion (HPP). We aimed to compare the influence of each mode of preservation and their combination on oxidative stress, perfusion characteristics and tissue damage, after a period of warm ischemia. Rat kidneys which had undergone ischemia (0, 30, 60 min) were preserved either by CS (12, 24 h), or by HPP (12 h), or by a combination of both (HPP+CS, CS+HPP), in University of Wisconsin cold storage solution (UWCSS) at + 4 degrees C. During HPP, renal vascular pressure decreased then increased to reach 90 mmHg after perfusion for 7 h. If HPP followed CS, the mean pressure reached 200 mmHg, showing successive high amplitude peaks. HPP had a deleterious effects on tissue structure with tubular necrosis, and induced an increase in catalase (Cat) and a decrease in manganese superoxide dismutase (Mn SOD) and gluthatione peroxidase (GPx) activity. Copper zinc superoxide dismutase (Cu/Zn SOD) activity was not reduced except with CS+HPP. During CS, we observed an increase in GPx, Cu/Zn SOD and Cat activity, a decrease in Mn SOD activity and no histological alterations in the kidney. CS induces a slight oxidative stress which is not important enough to induce major tissue damage. HPP with UWCSS induces a stronger stress, which overpowers the antioxidant defences, inducing tissue damage. The reperfusion of HPP with UWCSS emphasises the stress initiated by CS. In addition an increase in damage occurred in the CS + HPP group.