P-glycoprotein-associated chloride currents revealed by specific
block by an anti-p-glycoprotein antibody.
Han, Ernest S., Carlos G. Vanoye, Guillermo A. Altenberg, and Luis
Reuss.
Department of Physiology and Biophysics, University of Texas
Medical Branch, Galveston, Texas 77555-0641
APStracts 2:0408C, 1995.
The relationships between P-glycoprotein (Pgp) expression and plasma
-membrane ion currents activated by cell swelling were studied in
several cell lines using the whole-cell configuration of the patch
-clamp technique. Swelling-activated Cl- currents (ICls) had similar
characteristics in four cell lines, independent of whether or not Pgp
was expressed. Addition of the anti-Pgp monoclonal antibody C219 or
its Fab fragment to the pipette solution prevented ICls in cells
expressing functional Pgp (assessed by immunoblots,
immunofluorescence and transport of rhodamine 123), but not in cells
lacking Pgp expression. A peptide analog of the C219 epitope
abolished the effect of C219. Other anti-Pgp antibodies and mouse IgG
were ineffective. C219 did not alter swelling-activated cation
currents. Inasmuch as ICls is present in cells that do not express
Pgp and C219 has no effect on ICls in these cells, we conclude that
Pgp is not required for the ICls phenotype. However, when expressed
in the plasma membrane, Pgp is involved, directly or indirectly, in
ICls, but not in other swelling-activated currents.
Received 5 July 1995; accepted in final form 16 November 1995.
APS Manuscript Number C398-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95