Reduced DIDS-sensitive chloride conductance in Ae1-/- mouse erythrocytes.
The resting membrane potential of the human erythrocyte is largely determined by a constitutive Cl(-) conductance approximately 100-fold greater than the resting cation conductance. The 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)-sensitive electroneutral Cl(-) transport mediated by the human erythroid Cl(-)/HCO(3)(-) exchanger, AE1 (SLC4A1, band 3) is >10,000-fold greater than can be accounted for by the Cl(-) conductance of the red cell. The molecular identities of conductive anion pathways across the red cell membrane remain poorly defined. We have examined red cell Cl(-) conductance in the Ae1(-/-) mouse as a genetic test of the hypothesis that Ae1 mediates DIDS-sensitive Cl(-) conductance in mouse red cells. We report here that wildtype mouse red cell membrane potential resembles that of human red cells in the predominance of its Cl(-) conductance. We show with four technical approaches that the DIDS-sensitive component of erythroid Cl(-) conductance is reduced or absent from Ae1(-/-) red cells. These results are consistent with the hypothesis that the Ae1 anion exchanger polypeptide can operate infrequently in a conductive mode. However, the fragile red cell membrane of the Ae1(-/-) mouse red cell exhibits reduced abundance or loss of multiple polypeptides. Thus, loss of one or more distinct, DIDS-sensitive anion channel polypeptide(s) from the Ae1(-/-) red cell membrane cannot be ruled out as an explanation for the reduced DIDS-sensitive anion conductance.
Alper
Seth L
SL
Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA. salper@bidmc.harvard.edu
Vandorpe
David H
DH
Peters
Luanne L
LL
Brugnara
Carlo
C
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology*; D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000235:genetics* / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D004553:Electric Conductivity; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000502:physiology*; D004912:Erythrocytes / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D008564:Membrane Potentials / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008817:Mice, Mutant Strains; D018408:Patch-Clamp Techniques; D014634:Valinomycin / Q000494:pharmacology
D001457:Anion Exchange Protein 1, Erythrocyte; D002712:Chlorides; D007476:Ionophores; D008565:Membrane Proteins; C454201:SLC4A1 protein, human; C523515:Slc4a1 protein, mouse; D014634:Valinomycin; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid