Effects of cold ischemia on the preserved and transplanted rat kidney structural changes of the proximal tubule

Summary

The effects of cold ischemia on the proximal tubule of the rat kidney were studied by light and electron microscopy in vitro and also in vivo after transplantation. The duration of cold ischemia was chosen to that after transplantation the function of the kidneys was normal (2 h of ischemia), largely reduced (12 h) and almost abolished (16 h). The results showed that cold ischemia led to alterations of the proximal tubules in vitro which were reversible, judging from the fine-structural appearance. In vivo 24 h after transplantation of kidneys subjected to 12 and 16 h of cold ischemia small discrete areas of necrosis were seen in the proximal tubules, mainly in the pars recta in the outer stripe of the outer zone of the medulla. Changes in viable cells consisted of the occurrence of abundant absorption droplets in the cytoplasm of the tubular cells and of proteinaceous casts and cell debris in the tubular lumina. The more frequent necrosis in the pars recta in the outer stripe than in the pars convoluta was believed to be caused by a greater reduction of recirculating blood to this region than to the outer part of the cortex after transplantation. However, these necrotic areas were not sufficiently extensive to explain the marked decrease in function in these kidneys.