Morphologic changes in tubular cells from in situ kidneys following experimental hypothermia and rewarming

Abstract

Although renal failure may occur following rewarming from deep accidental hypothermia, this subject has received little attention in experimental hypothermia and clinical case reports. In order to explore the integrity of hypothermic and posthypothermic renal morphology we used an experimental animal model of accidental hypothermia where the heart supports the circulation throughout cooling and rewarming without accompanying cardioplegia or ischemia. Ultrastructural changes in renal tubular cells from three groups of pentobarbital anesthetized Wistar rats: 1) controls (n=6) maintained at 37 degrees C for 4 h, 2) hypothermic rats (n=6) core-cooled and maintained at 15-13 degrees C for 4 h, and 3) rewarmed rats (n=10), were studied as a sensitive indicator of renal damage. Electron micrographs (EM) from hypothermic kidneys showed rounded up mitochondria with loss of contrast. These changes were observed in several though not all of the biopsies, but they were found in all kidneys. Areas exhibiting focal tubular necrosis were seen on most EM from three of these kidneys. EM from rewarmed kidneys showed alterations of mitochondrial ultrastructure with similarities to those observed after hypothermia, but in general the changes were more prominent. Extracellular edema, intracellular edema, swelling of mitochondria, margination of chromatin, necrosis of single tubular cells, and disrupting necrotic debris into tubular lumen could be found in micrographs from 7 of the 10 kidneys examined. Rewarming from experimental hypothermia, without episodes of ischemia or hypoxia, thus induces ultrastructural changes in renal tubular cells similar to changes observed in acute tubular necrosis, associated with renal failure.

Prognostic Factors and a Prognostic Index for Cats with Acute Kidney Injury

“…It is well known that the kidney plays a role in thermogenesis, and that nephrectomized animals have lower core temperature; in these circumstances, it is quite probable that hypothermia might occur due to renal disease. Additionally, in an experimental study, hypothermia has been found to induce ultrastructural changes in renal tubular cells and these changes were similar to acute tubular necrosis . Therefore, a low body temperature might result from renal injury and may then lead to further renal functional deficiencies.…”

Oxidative stress evaluation of ischemia and reperfusion in kidneys under various degrees of hypothermia in rats

“…It is known that is easier to obtain mild or moderate cooling, and that deep hypothermia is more associated with thermal injury of tissue. Also, it is important to mention that slight hypothermia has a lesser interference in the systemic temperature 4 . Although the demonstration that mild hypothermia is sufficient to offer liver protection against the deleterious actions of I/R, there are no studies concerning the kidney 2,3 .…”

Effects of Prolonged Warm and Cold Ischemia in a Solitary Kidney Animal Model after Partial Nephrectomy: An Ultrastructural Investigation

“…Previous studies have described the various structural changes in the podocytes in challenging situations [8][9][10][11][12][13][14][15][16][17][18][19][20]. These changes include mostly foot process effacement, cell body attenuation, pseudocyst formation, and fusion of the podocytes to the GBM.…”