Toggle Main Menu Toggle Search

Open Access padlockePrints

Kinetics and regulation of a Ca2+-activated Cl- conductance in mouse renal inner medullary collecting duct cells

Lookup NU author(s): Dr Stefan Boese, Omar Aziz, Professor Nicholas Simmons, Dr Michael Gray

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


Abstract

Using the whole cell patch-clamp technique, a Ca2+-activated Cl- conductance (CaCC) was transiently activated by extracellular ATP (100 μM) in primary cultures of mouse inner medullary collecting duct (IMCD) cells and in the mouse IMCD-K2 cell line. ATP also transiently increased intracellular Ca2+ concentration ([Ca2+]i) from ∼100 nM to peak values of ∼750 nM in mIMCD-K2 cells, with a time course similar to the ATP-induced activation and decay of the CaCC. Removal of extracellular Ca2+ had no major effect on the peak Cl- conductance or the increase in [Ca2+]i induced by ATP, suggesting that Ca2+ released from intracellular stores directly activates the CaCC. In mIMCD-K2 cells, a rectifying time- and voltage-dependent current was observed when [Ca2+]i was fixed via the patch pipette to between 100 and 500 nM. Maximal activation occurred at ∼1 μM [Ca2+]i, with currents losing any kinetics and displaying a linear current-voltage relationship. From Ca2+-dose-response curves, an EC50 value of ∼650 nM at ∼80 mV was obtained, suggesting that under physiological conditions the CaCC would be near fully activated by mucosal nucleotides. Noise analysis of whole cell currents in mIMCD-K2 cells suggests a single-channel conductance of 6-8 pS and a density of ∼5,000 channels/cell. In conclusion, the CaCC in mouse IMCD cells is a low-conductance, nucleotide-sensitive Cl- channel, whose activity is tightly coupled to changes in [Ca2+]i over the normal physiological range.


Publication metadata

Author(s): Boese SH, Aziz O, Simmons NL, Gray MA

Publication type: Article

Publication status: Published

Journal: American Journal of Physiology - Renal Physiology

Year: 2004

Volume: 286

Issue: 4

Pages: F682-F692

ISSN (print): 0363-6127

ISSN (electronic): 1522-1466

Publisher: American Physiological Society

URL: http://dx.doi.org/10.1152/ajprenal.00123.2003

DOI: 10.1152/ajprenal.00123.2003

PubMed id: 14678946


Altmetrics

Altmetrics provided by Altmetric


Share