LOSS OF CYTOSKELETAL SUPPORT IS NOT SUFFICIENT FOR ANOXIC PLASMA-MEMBRANE DISRUPTION IN RENAL-CELLS

The goal of this study was to determine whether anoxic membrane disrup tion is initiated by loss of cytoskeletal support in rabbit renal prox imal tubules (PT). We specifically tested 1) whether cytoskeletal pert urbation affects membrane integrity under normoxia, 2) whether cytoske letal perturbation potentiates anoxic membrane damage, and 3) whether the membrane protection by glycine depends on cytoskeletal integrity. Cytoskeletal perturbation was achieved with 10 mu M cytochalasin D (CD ) because it selectively disturbs F-actin organization and has similar effects as anoxia on the cytoskeleton of PT. During normoxia, CD caus ed decreased basal F-actin content, microvillar breakdown, and membran e-cytoskeleton dissociation, as revealed by the use of laser tweezers. However, membrane integrity was not altered by CD, as monitored by la ctate dehydrogenase release. CD pretreatment of PT did not potentiate anoxic membrane damage. Finally, plasma membrane protection by glycine during anoxia remained in CD-pretreated PT despite loss of cytoskelet al support. These results demonstrate that loss of cytoskeletal suppor t is not sufficient for anoxic plasma membrane disruption.