Abstract

Cell swelling following hypoosmotic stress leads to the activation of volume-sensitive ion channels that allow a K+ and Cl- efflux accompanied by water loss. A Ca2+-insensitive K+ channel (IK,vol) has been described in Ehrlich cells that can be activated by hypotonicity and leukotriene D4 and is inhibited by clofilium. We have studied the activation and deactivation by osmotic stimuli of this channel. A G-protein appears to be involved in these processes since GTP-?-S accelerates deactivation, while GDP-?-S blocks the channel in the open state, a result mimicked by pertussis toxin (PTX). In addition, PTX accelerates the onset of IK,vol. We propose that IK,vol is tonically inhibited by a PTX-sensitive G-protein. © 2002 Elsevier Science B.V. All rights reserved.