Improved function of perfused rabbit kidneys by prevention of oxidative injury

This study explored the effect of adding small amounts of the reducing agents ascorbic acid and glutathione to a Ringer's-albumin perfusate used for 24-hr hypothermic perfusion of rabbit kidneys. Maintenance of function during preservation was evaluated with a shunt perfusion model and by measuring the ability of cortical slices to restore normal K/Na ratios after incubation in a electrolyte medium. When placed in contact with the unmodified perfusate, an electrode of pyrolytic carbon registered a potential of +190 mV relative to the silver-silver chloride couple. This reading fell rapidly by 100-125 mv when kidneys were placed on the circuit. The mean creatinine clearance after 24-hr perfusion was significantly improved from 162 +/- 56 ml/hr in controls to 284 +/- 92 ml/hr when the potential indicated by this electrode was preadjusted to 43-54 mv with reducing agents, and to 237 +/- 62 ml/hr when this adjustment was made after 2 hr. These creatinine clearances were similar to those of kidneys stored on ice for only 1 hr. These findings indicate minimal injury occurred in the chemically reduced groups and emphasize the importance of preventing oxidative damage to kidneys during hypothermic organ perfusion. The time course of the changes in potential registered by this electrode was consistent with our previous finding that much of the damage to perfused kidneys occurs very early in the course of perfusion. The tissue slice studies showed no detectable damage to the renal parenchyma of the kidneys in the control group despite diminished creatinine clearance. This suggests that the site of oxidation injury is the vascular compartment.