Referenced in: none

Automatically associated channels: SK3

Title: Cell swelling activates cloned Ca(2+)-activated K(+) channels: a role for the F-actin cytoskeleton.

Authors: Nanna K Jorgensen, Stine F Pedersen, Hanne B Rasmussen, Morten Grunnet, Dan A Klaerke, Søren-Peter Olesen

Journal, date & volume: Biochim. Biophys. Acta, 2003 Sep 2 , 1615, 115-25

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/12948593

Abstract
Cloned Ca(2+)-activated K(+) channels of intermediate (hIK) or small (rSK3) conductance were expressed in HEK 293 cells, and channel activity was monitored using whole-cell patch clamp. hIK and rSK3 currents already activated by intracellular calcium were further increased by 95% and 125%, respectively, upon exposure of the cells to a 33% decrease in extracellular osmolarity. hIK and rSK3 currents were inhibited by 46% and 32%, respectively, by a 50% increase in extracellular osmolarity. Cell swelling and channel activation were not associated with detectable increases in [Ca(2+)](i), evidenced by population and single-cell measurements. In addition, inhibitors of IK and SK channels significantly reduced the rate of regulatory volume decrease (RVD) in cells expressing these channels. Cell swelling induced a decrease, and cell shrinkage an increase, in net cellular F-actin content. The swelling-induced activation of hIK channels was strongly inhibited by cytochalasin D (CD), in concentrations that caused depolymerization of F-actin filaments, indicating a role for the F-actin cytoskeleton in modulation of hIK by changes in cell volume. In conclusion, hIK and rSK3 channels are activated by cell swelling and inhibited by shrinkage. A role for the F-actin cytoskeleton in the swelling-induced activation of hIK channels is suggested.