Left kidneys of rats were made ischemic for 25 minutes and proximal tubule brush border alterations studied in the S1 and S2 segments. Scanning electron microscopy revealed that brush border microvilli became unstable, fused with one another, and were interiorized into proximal tubule cytoplasm soon after reflow of blood following ischemia. Rapid regeneration followed; scanning electron microscopy showed that regneration occurred in a fashion whereby clusters of microvilli in flower-like configurations were extruded from the cell interior toward the surface. Such unique patterns of microvillus formation have not been reported before. Activity of the brush border enzymes, alkaline phosphatase and maltase, were not significantly depressed throughout the cycle of brush border loss and regneration. Likewise, there were no alterations in the activity of β-glucuronidase, a lysosomal enzyme. Alkaline phosphatase cytochemistry showed that microvillus membranes that were interiorized into the cell cytoplasm retained enzyme activity on their surfaces during the early period of brush border loss as well as during regeneration. These results strongly suggest that in reversibly injured proximal tubule cells regeneration of the brush border occurs primarily by a process of recycling of damaged, previously incorporated membrane. The nature of the initial membrane damage and the mechanism of recycling remain unknown.
|Original language||English (US)|
|Number of pages||11|
|State||Published - Dec 1 1981|
ASJC Scopus subject areas
- Pathology and Forensic Medicine
- Molecular Biology
- Cell Biology