Cells respond to swelling by activating anion and cation channels that allow the passive loss of inorganic ions and organic solutes. Net solute efflux accompanied by osmotically obliged water functions to return cell volume towards its original value, a process termed regulatory volume decrease.
An apparently ubiquitous response to swelling in vertebrate cells is activation of an outwardly rectifying anion current termed ICl.swell. The general characteristics of this current include an Eisenman type I anion permeability sequence (I− > Br− > Cl− > F−), modest outward rectification, voltage-dependent inactivation at potentials above ECl, inhibition by a wide variety of compounds, including conventional anion transport inhibitors, and block by extracellular nucleotides such as ATP (reviewed by Strange et al., 1996; Okada, 1997). The degree of rectification, voltage sensitivity, and pharmacology can vary somewhat between different cell types. It is...
