REGENERATION OF ATP IN KIDNEY SLICES AFTER WARM ISCHEMIA AND HYPOTHERMIC PRESERVATION

The current shortage of cadaveric kidneys may be alleviated to some de gree by increasing our capabilities to use less than ideal donor kidne ys, such as those from non-heart-beating donors. These kidneys are oft en exposed to no flow (ischemia) for varying lengths of time. Full uti lization of these kidneys may require better methods of organ preserva tion that could reverse existing ischemic injury. This may conceivably require that, during preservation, energy stores (ATP) lost during wa rm ischemia be recharged. This would require continuous perfusion. Usi ng a kidney slice model, we investigated the effects of simulated hypo thermic machine perfusion with the UW gluconate perfusate on the capab ility of rabbit kidneys exposed-to warm ischemia to regenerate ATP. Af ter 30 min of warm ischemia, ATP content was low (0.2 mu mol/g wet wei ght) but increased to 0.7-0.9 mu mol/g wet weight after 24 h of simula ted machine perfusion at 4 degrees C. After an additional 2 h of rewar ming (37 degrees C in oxygenated Krebs Henseleit buffer), the slice AT P content increased to about 1.0 mu mol/g wet weight (similar to kidne ys not exposed to warm ischemia) when the antioxidants desferrioxamine and N-2-(mercaptopropionyl) glycine were included in the preservation media. Significantly less ATP was present without the antioxidants. A fter 60 min of warm ischemia, less ATP was regenerated after 24 h of s imulated machine perfusion (about 0.4 mu mol/g wet weight) than after 30 min of warm ischemia. However, more ATP was regenerated when antiox idants were included in the perfusate (0.4 vs 0.8 mu mol/g wet weight) . This study shows that ATP can be regenerated in kidneys exposed to w arm ischemia by continuous perfusion in the UW gluconate solution. Fur thermore, oxygen free radicals appear to cause suppression of ATP rege neration since an iron and a hydroxyl radical scavenger improved ATP f ormation. The ATP content of kidneys exposed to 60 min of WI was less than after 30 min of warm ischemia, suggesting that better methods of preservation may be needed to improve our capability to utilize kidney s damaged by extensive warm ischemia (> 60 min). This may require the development of new methods and/or perfusates for kidney preservation.