Redistribution of microvilli and membrane enzymes in isolated rat proximal tubule cells.

Isolated cells from the proximal tubule have previously been used to study specific renal physiological processes. Here we analysed the structural changes induced by mechanical isolation on rat proximal tubule cells. As major modifications we detected: 1) a redistribution of brush border microvilli, which spread out over all the cell surface immediately after isolation; 2) a rapid redistribution of the apical membrane enzyme markers aminopeptidase N and isomaltase; and 3) a striking decrease of membrane surface amplification factor. The results show that cells isolated from the proximal tubule rapidly loose their characteristic polarized membrane structure. Loss of epithelial polarity implies loss of several vectorial transports and should thus be cautiously taken into account when working with this model system.