The influence of hypoxic cell-free perfusion and ischemia on cell morphology in the proximal tubular S2-segment of the rat kidney

Abstract
In the present study, in-situ perfused rat kidneys were used as a model to demonstrate the different morphological changes induced by various periods of warm ischemia or of warm hypoxic cell-free perfusion. Light and electron microscopic evaluation revealed no changes in the S2 proximal tubular cells after short exposure times of up to 4 min, whereas longer periods resulted in changes ranging from slight alterations (at 10 min) to severe damage (at 60 min). Warm hypoxic cell-free perfusion induced obvious alterations in the proximal tubular cells somewhat sooner than warm ischemia. The microscopical findings were consistent with the statistics of a detailed morphometrical analysis performed on the mitochondrial diameter. The results were further substantiated by counting intramitochondrial electron-dense condensations (‘flocculent densities’) as indicators of irreversible cell alteration.