Proximal tubule morphology in rats with renal congestion: a study involving the in vivo cryotechnique.

The present study aimed to examine the changes induced in proximal tubules by renal congestion using the in vivo cryotechnique (IVCT). Twelve male Wistar rats were divided into four equal groups: group 1 (the control); groups 2 and 3, which were subjected to 2 and 5 min of congestion, respectively; and group 4, which was subjected to 5 min of congestion followed by 10 min of recirculation. Under anesthesia, renal congestion was induced in the bilateral kidneys by ligating the inferior vena cava just above the branching renal veins. The left kidneys, which were subjected to the IVCT, were then compared with the right kidneys, which underwent a conventional fixation method. Among the left kidneys, the proximal tubules in group 1 consisted of cuboidal cells and had open lumina. In the congestive groups, the diameters of the proximal tubules were increased, and their lumina were obstructed by swollen cells and ischemia-associated cell debris. In group 4, the proximal tubules were still dilated, as seen in the congestive groups; however, the swollen cells had recovered their cuboidal form, and the cell debris had disappeared from the tubules' lumina. The present study demonstrated the in vivo morphology of proximal tubules in living rats subjected to congestion, which was unclear using conventional fixation methods.