A voltage-independent K+ conductance activated by cell swelling in Ehrlich cells is modulated by a G-protein-mediated process

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 (I-K.vol) has been described in Ehrlich cells that can be activated by hypotonicity and leukotriene D-4 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-gamma-S accelerates deactivation, while GDP-beta-S blocks the channel in the open state, a result mimicked by pertussis toxin (PTX). In addition, PTX accelerates the onset of I-K.vol. We propose that I-K.vol is tonically inhibited by a PTX-sensitive G-protein. (C) 2002 Elsevier Science B.V. All rights reserved.