TY - JOUR
T1 - Deformation of swollen erythrocytes provides a model of sickling-induced leak pathways, including a novel bromide-sensitive component
AU - Sugihara, Takashi
AU - Yawata, Yoshihito
AU - Hebbel, Robert P.
PY - 1994/5/1
Y1 - 1994/5/1
N2 - Deoxygenation-induced red blood cell (RBC) sickling probably activates multiple cation leak pathways. In an attempt to model this, we examined the net passive K efflux ('K leak') from normal and sickle RBCs undergoing elliptical deformation in hypotonic media (200 mOsmol/L). This hypotonic deformation activates two deformation-dependent K leak pathways that are not detectable during the balanced leak (K(efflux) = Na(influx)) resulting from deformation of RBCs in isotonic medium. These are (1) a calcium-dependent leak component and (2) a novel leak pathway that is inhibited by substitution of bromide (but not sulfamate) for chloride, which converts the unbalanced K leak (K(efflux) > Na(influx)) of hypotonic deformation to a residual balanced leak. This dramatic effect of hypotonic deformation is reversible, is detected in both normal and sickle RBCs, and is inhibited significantly by 4,4'-diisothiocyano-2,2'-stilbene disulfonate. Remarkably, bromide also inhibits by 55% the K leak resulting from authentic deoxygenation-induced RBC sickling and, thereby, blunts the imbalance of accompanying monovalent cation leaks. The unique effect of bromide is not readily explainable on the basis of known behaviors of known ion leak/transport pathways. The mechanical threshold for triggering K leak during hypotonic deformation is at applied shear stress of 164 dyne/cm2, a value similar to the abnormal susceptibility we previously found for oxygenated sickle RBCs during isotonic deformation. These data suggest that membrane stretch accompanying hypotonic deformation activates the same multiple leak pathways that contribute to net K leak during authentic RBC sickling, including a previously unknown bromide- sensitive leak.
AB - Deoxygenation-induced red blood cell (RBC) sickling probably activates multiple cation leak pathways. In an attempt to model this, we examined the net passive K efflux ('K leak') from normal and sickle RBCs undergoing elliptical deformation in hypotonic media (200 mOsmol/L). This hypotonic deformation activates two deformation-dependent K leak pathways that are not detectable during the balanced leak (K(efflux) = Na(influx)) resulting from deformation of RBCs in isotonic medium. These are (1) a calcium-dependent leak component and (2) a novel leak pathway that is inhibited by substitution of bromide (but not sulfamate) for chloride, which converts the unbalanced K leak (K(efflux) > Na(influx)) of hypotonic deformation to a residual balanced leak. This dramatic effect of hypotonic deformation is reversible, is detected in both normal and sickle RBCs, and is inhibited significantly by 4,4'-diisothiocyano-2,2'-stilbene disulfonate. Remarkably, bromide also inhibits by 55% the K leak resulting from authentic deoxygenation-induced RBC sickling and, thereby, blunts the imbalance of accompanying monovalent cation leaks. The unique effect of bromide is not readily explainable on the basis of known behaviors of known ion leak/transport pathways. The mechanical threshold for triggering K leak during hypotonic deformation is at applied shear stress of 164 dyne/cm2, a value similar to the abnormal susceptibility we previously found for oxygenated sickle RBCs during isotonic deformation. These data suggest that membrane stretch accompanying hypotonic deformation activates the same multiple leak pathways that contribute to net K leak during authentic RBC sickling, including a previously unknown bromide- sensitive leak.
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U2 - 10.1182/blood.v83.9.2684.bloodjournal8392684
DO - 10.1182/blood.v83.9.2684.bloodjournal8392684
M3 - Article
C2 - 7513211
AN - SCOPUS:0028269609
SN - 0006-4971
VL - 83
SP - 2684
EP - 2691
JO - Blood
JF - Blood
IS - 9
ER -