Loss of plasma membrane structural support in atp depleted renal
epithelia.
Doctor, R. Brian, Doncho V. Zhelev, and Lazaro J. Mandel.
Dept. of Cell Biology, Division of Physiology and Cellular
Biophysics, Duke University Medical Center, Durham, NC 27710
APStracts 3:0284C, 1996.
Renal ischemia induces cytoskeletal alterations, membrane
perturbations, including bleb formation, and, ultimately, membrane
lysis. The mechanisms which underlie these alterations are largely
unknown. Using isolated rat renal proximal tubule fragments and
calibrated micropipette techniques, two potential mechanisms for
membrane bleb formation during ATP depletion were examined: (1)
decreased cytoskeletal retention of the plasma membrane and (2)
increased intracellular pressure. Under control conditions, the
pressure required to pull the membrane from the underlying cellular
matrix was 73 + 10 kdyn.cm-2. After 30 min of ATP depletion, this
pressure was diminished by >95% and blebs began to emerge from
the basal membrane. The intracellular pressure within these blebbed
cells was only 0.08 + 0.02 kdyn.cm-2. These observations indicate
that, during ATP depletion, the strength of membrane retention
diminished until the relatively low intracellular pressure was
capable of driving membrane bleb formation. Cytochalasin D, which
disrupts the actin cytoskeleton, decreased the strength of membrane
retention by 65 + 7%. This suggests that, during ATP depletion,
alterations of the actin cytoskeleton may mediate the loss of
membrane retention.
Received 1 May 1996; accepted in final form 7 August 1996.
APS Manuscript Number C231-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996