Figure 137

Functional and morphologic changes in tight junction integrity associated with ischemic injury or intracellular ATP depletion. A and B, Ruthenium red paracellular permeability in rat proximal tubules. A, In control kidneys, note the electron-dense staining of the brush border, which cuts off at the tight junctions (tj, arrows). B, Sections from a perfusion-fixed kidney after 20 minutes of renal artery cross-clamp [35]. The electron-dense staining can be seen at cell contact sites beyond the tight junction (arrows). The paracellular pathway is no longer sealed by the tight junction, permitting backleak of the electron-dense ruthenium red. C, Changes in the transepithelial resistance (TER) versus time during ATP depletion and ATP repletion [36]. Paracellular resistance to electron movement

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