Regulation of an Outwardly Rectifying Chloride Conductance in Renal Epithelial Cells by External and Internal Calcium (original) (raw)

Abstract.

We have used perforated patch clamp and Fura-2 microfluorescence measurements to study Ca2+-activated Cl− currents in cultured mouse renal inner medullary collecting duct cells (mIMCD-3). The conductance was spontaneously active under resting conditions and whole cell currents were time and voltage-independent with an outwardly rectifying current-voltage relationship. The channel blockers DIDS, niflumic acid, glybenclamide and NPPB reversibly decreased the basal currents, whereas the sulfhydryl agent, DTT produced an irreversible inhibition. Increasing or decreasing extracellular calcium produced parallel changes in the size of the basal currents. Variations in external Ca2+ were associated with corresponding changes in free cytosolic Ca2+ concentration. Increasing cytosolic Ca2+ by extracellular ATP or ionomycin, further enhanced Cl− conductance, with whole cell currents displaying identical biophysical properties to the basal currents. However, the agonist-stimulated currents were now increased by DTT exposure, but still inhibited by the other channel blockers. Using RT-PCR, three distinct mRNA transcripts belonging to the CLCA family of Ca2+-activated Cl− channel proteins were identified, two of which represent novel sequences. Whether different channels underlie the basal and agonist-stimulated currents in mIMCD-3 cells is unclear. Our findings establish a novel link between alterations in external and internal Ca2+ and the activity of Ca2+-activated Cl− transport in these cells.

Access this article

Log in via an institution

Subscribe and save

Buy Now

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Similar content being viewed by others

Author information

Authors and Affiliations

  1. Department of Physiological Sciences, University Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK, , , , , , GB
    G.S. Stewart, M. Glanville, O. Aziz, N.L. Simmons & M.A. Gray

Authors

  1. G.S. Stewart
    You can also search for this author inPubMed Google Scholar
  2. M. Glanville
    You can also search for this author inPubMed Google Scholar
  3. O. Aziz
    You can also search for this author inPubMed Google Scholar
  4. N.L. Simmons
    You can also search for this author inPubMed Google Scholar
  5. M.A. Gray
    You can also search for this author inPubMed Google Scholar

Additional information

Received: 17 July 2000/Revised: 30 November 2000

Rights and permissions

About this article

Cite this article

Stewart, G., Glanville, M., Aziz, O. et al. Regulation of an Outwardly Rectifying Chloride Conductance in Renal Epithelial Cells by External and Internal Calcium.J. Membrane Biol. 180, 49–64 (2001). https://doi.org/10.1007/s002320010058

Download citation