Lipid hydroperoxides permit deformation-dependent leak of monovalent cation
from erythrocytes
T Sugihara, W Rawicz, EA Evans and RP Hebbel
Department of Medicine, University of Minnesota, Minneapolis.
Subtle peroxidative perturbation of normal red blood cells (RBC) using
t-butylhydroperoxide creates a leak pathway for monovalent cations that is
reversibly activated by cell deformation. To determine what factor promotes
expression of this unique membrane defect, we have dissected "peroxidation"
into components that can be evaluated separately by comparing K leak from
suitably modified RBC during elliptical deformation and parallel control
incubation. Selective introduction of phospholipid hydroperoxides into
normal RBC membranes successfully induces a deformation-dependent leak
pathway having the same phenomenology as that previously documented for
cells treated with t- butylhydroperoxide itself (fully recoverable;
calcium-independent; inhibited at lower pH; K efflux balanced by Na
influx). This leak pathway occurs in the absence of detectable secondary
peroxidative change and appears to reflect a direct influence of lipid
hydroperoxide. Using micropipette examination of vesicular bilayers
reconstituted from RBC lipid extracts, we find that lipid from peroxidized
RBC exhibits only a slight tendency to be less cohesive than normal lipid,
apparently precluding isolated lipid properties as an explanation for
altered permeability barrier function. However, addition of a hydrophobic
membrane-spanning peptide to these same lipids significantly diminishes
bilayer cohesion, an effect that is exacerbated further by the presence of
peroxidized lipid. These observations suggest that lipid hydroperoxide is a
necessary, but perhaps not sufficient, factor for induction of this unique
leak pathway. Our results may be relevant to the abnormal cation
homeostasis of sickle RBC in which deformation of an oxidatively perturbed
membrane occurs during the sickling phenomenon.
Volume 77,
Issue 12,
pp. 2757-2763,
06/15/1991
Copyright © 1991 by The American Society of Hematology
