text: Active metabolism of glucose with production of bicarbonate has been demonstrated by Pettersson and Cohen.
  Pettersson studies were on the metabolism of glucose and fatty acids by kidneys during 6 day hypothermic perfusion storage and he found that the kidneys consumed glucose at 4.4 μmol/g/day and fatty acids at 5.8 μmol/g/day. In Cohens study the best 8 day stored kidneys consumed glucose at the rate of 2.3 μmol/g/day and 4.9 μmol/g/day respectively which made it likely that they were using fatty acids at similar rates to Petterssons dogs' kidneys. The constancy of both the glucose consumption rate and the rate of bicarbonate production implied that no injury was affecting the glycolytic enzyme or carbonic anhydrase enzyme systems.
  Lee showed that fatty acids were the preferred substrate of the rabbits kidney cortex at normothermic temperatures, and glucose the preferred substrate for the medullary cells which normally metabolise anaerobically. Abodeely showed that both fatty acids and glucose could be utilised by the outer medulla of the rabbits kidney but that glucose was used preferentially. At hypothermia the metabolic needs of the kidney are much reduced but measurable consumption of glucose, fatty acids and ketone bodies occurs. Horsburgh showed that lipid is utilised by hypothermic kidneys, with palmitate consumption being 0-15% of normal in the rat kidney cortex at 15 °C. Pettersson showed that, on a molar basis, glucose and fatty acids were metabolised by hypothermically perfused kidneys at about the same rates. The cortex of the hypothermic dog kidney was shown by Huang to lose lipid (35% loss of total lipid after 24 hours) unless oleate was added to the kidney perfusate. Huang commented that this loss could affect the structure of the cell and that the loss also suggested that the kidney was utilising fatty acid. In a later publication Huang showed that dog kidney cortex slices metabolised fatty acids, but not glucose, at 10 °C.
  Even if the correct nutrients are provided, they may be lost by absorption into the tubing of the preservation system. Lee demonstrated that silicone rubber (a material used extensively in kidney preservation systems) absorbed 46% of a perfusate's oleic acid after 4 hours of perfusion.