Oxidation-reduction maintenance in organ preservation

The isolated perfused organ is more sensitive to the toxicity of oxygen since hypothermia reduces the activities of enzymes responsible for minimizing oxygen toxicity. To protect the organ under these conditions reducing agents must be added to the perfusate. Quantitation of the resulting reduction is best obtained by measurement of the oxidation-reduction potential of the perfusate. A device was designed for this purpose and, by electrochemical principle, controlled reduction of the oxidized form of the oxidation-reduction couple was affected. Kidneys were perfused with cryoprecipitated plasma. With the electrochemical cell in the circuit, the oxidation-reduction potential of the perfusate was adjusted by the addition of ascorbic acid and glutathione and the cell was driven by a battery-powered potentiostat. Kidneys subjected to 60 minutes of warm ischemia had optimal survival at -20 mV. Preservation for six days in a monitored group had no survivors, whereas kidneys with oxidation-reduction support maintained life. Optimal oxidation-reduction support maintained life. Optimal oxidation-reduction was at or near -17 mV. These data show a requirement of an optimal oxidation-reduction potential to reverse warm ischemia damage and to prolong the period of ex vivo preservation of isolated perfused organ.