Perspective: The List of Potential Volume-sensitive Chloride Currents Continues to Swell (and Shrink)

The protein for the swelling-activated chloride conductance is one of the few ion channels left for which we do not have a universally acceptable clone. In this brief note, I hope to describe why chloride channels in general, and I_Cl.swell in particular, have been difficult to pin down. Dr. Strange describes why he believes the pICln protein is not I_Cl.swell. I agree. In 1995 we demonstrated that pICln is unlikely to be a channel itself (Krapivinsky et al., 1994). Voets et al. (1996) also concludes that, although oocyte expression of pICln activates a chloride current, this chloride current is not I_Cl.swell. pICln is related to chloride channel activation, but how or why is not understood. In an attempt to place the arguments in a broader perspective, Table I lists most of the proposed chloride channel proteins that have been isolated and cloned...