Respiratory changes in isolated perfused rat kidneys after freeze-thaw and hypothermic storage

Summary Oxygen consumption was measured in isolated rat kidneys before and after various types of damage. The kidneys were perfused with an asanguineous medium at 20 to 21°C and the pO 2 of the perfusate was recorded by a polarographic electrode. Autolysis at 37°C for 5 hrs invariably reduced oxygen uptake significantly. Quick freezing markedly increased oxygen uptake and a slower freezing rate produced a moderate increase. Dimethyl sulfoxide markedly decreased the quick freeze effect; this agent had no direct effect on O 2 uptake. Treatment with streptolysin O, a known cytolytic agent, mimicked the effects of freezing. It was concluded that increased oxygen uptake produced by freezing and by streptolysin resulted from membrane damage and the decrease caused by autolysis from enzyme decrease caused by autolysis from enzyme degradation. Kidneys stored at 4°C for 24 hrs exhibited no change in oxygen consumption, but after 48 and 72 hrs of storage oxygen uptake had increased significantly. A combination of metabolic inhibitors failed to alter this response. Oxygen uptake rate clearly cannot be used as an index of the functional integrity of the stored kidney but is useful in detecting two types of cell damage and in the study of cryoprotective agents.