The Journal of Membrane Biology

, Volume 201, Issue 3, pp 139–155

Time-dependent Interactions of Glibenclamide with CFTR: Kinetically Complex Block of Macroscopic Currents

Articles

DOI: 10.1007/s00232-004-0712-9

Cite this article as:
Zhang, ZR., Cui, G., Zeltwanger, S. et al. J Membrane Biol (2004) 201: 139. doi:10.1007/s00232-004-0712-9

Abstract

Blockade of the CFTR chloride channel by glibenclamide was studied in Xenopus oocytes using two-electrode voltage-clamp recordings, macropatch recordings, and summations of single-channel currents, in order to test a kinetic model recently developed by us from single-channel experiments. Both the forward and reverse macroscopic reactions, at negative and positive membrane potential VM, respectively, were slow in comparison to those reactions for other CFTR pore blockers such as DPC and NPPB, resulting in prominent relaxations on the order of tens of milliseconds. The rate of the reverse reaction was voltage-dependent, and dependent on the Cl driving force, while that of the forward reaction was not. In inside-out macropatches, block and relief from block occurred in two distinct phases that differed in apparent affinity. The results are consistent with the presence of multiple glibenclamide binding sites in CFTR, with varying affinity and voltage dependence; they support the kinetic model and suggest experimental approaches for identification of those sites by mutagenesis.

Keywords

Cystic fibrosis transmembrane conductance regulatorChloride ChannelBlockerABC TransporterSulfonylurea

Copyright information

© Springer 2004

Authors and Affiliations

  • Z.-R. Zhang
    • 1
  • G. Cui
    • 1
  • S. Zeltwanger
    • 2
  • N.A. McCarty
    • 1
  1. 1.School of BiologyGeorgia Institute of TechnologyAtlantaUSA
  2. 2.Department of PhysiologyEmory University School of MedicineAtlantaUSA